Sheldon is working late in his office thoroughly frustrated since it’s after nine o’clock. After a sudden blackout, Sheldon finds "blood" dripping down the walls. Then he is scared by a phosphorus-covered skeleton on a zip line. Sheldon is not impressed as Howard and Raj join him in his office. Sheldon turns around to find Leonard in a Balok mask from Star Trek causing Sheldon to faint.
At the comic book store, while Sheldon discusses his Texas background meaning that there will be revenge. A good looking girl wanders into the store which Stuart tries to talk to but can’t. She picks up a Hellboy comic book that Leonard was purchasing and then connects with her. (You’re cute.) She offers to make a trade for that one and gives him her phone number. Howard and Stuart were impressed. Stuart takes his picture for the store’s "Wall of Heroes" display.
Sheldon booby traps the mailbox on Leonard, but Leonard turns the prank around and gets Sheldon with it. Sheldon might be from Texas; however, Leonard is from New Jersey.
Leonard gets together with Alice, where he shows her a drawing Jim Lee drew of him at Comic-Con. Alice shows him a comic she drew based on her life including her having sex with half of a Chewbacca. She then kisses him and they start to make out, while she offers to trade Leonard her comic for the Hellboy comic. Leonard then offers her his car.
Sheldon's next target: Raj where he hides a snake in Raj's desk. Raj opens it and sees the cute snake and takes him to the biology lab to get it some mice.
Leonard goes over to talk to Penny about his personal relationship dilemma. He wants both Priya and Alice. He wants be one of those guys who sneaks around and sleeps with more than one woman. Penny tells him that he is looking for a way to sleep with both women and have everybody be happy about it. That’s what he’s looking for.Sheldon then approaches Howard with a joy buzzer and wants to shake his hand for various reasons. He hears Bernadette who now is sounding more like Howard's mother. Sheldon shocks Howard who drops to the floor and collapses due to his heart condition. Sheldon freaks out and Bernadette insists that he has to jab a needle of adrenaline into his heart because she isn't strong enough. Sheldon does it and then Howard wakes up because they pranked him. Sheldon can't believe he got duped and face palms himself getting stung by his own buzzer.
After consulting with Sheldon about his dilemma, Leonard actually had good advice from Nietzsche, morality is the fiction created by the weak masses to hold back the strongest in society.
Leonard has a formal date with Alice. As they are heading toward sex, Leonard’s conscience gets the better of him. He tells her that he has a girlfriend which seriously annoys Alice who calls him just another jerk. Leonard explains that he is a good guy and wants to just be friends. She throws him out of the apartment. As Leonard walks down the hall, he calls himself an idiot.
Leonard confesses the incident to Priya over videoconference, and she instantly forgives him. Leonard first thinks she is wonderful and then asks why. She confesses to having sex|slept with an ex-boyfriend. Leonard is very unhappy. Priya explains that it isn’t a contest. Leonard disagrees and tells her that she won ending the call. And then Leonard gets the crap scared out of him by Sheldon hiding inside the couch jumping out dressed as a zombie. (Bazinga, punk! Now we're even!)
- Guest starring:
- Teleplay: Bill Prady, Steven Molaro & Steve Holland
- Story: Chuck Lorre, Dave Goetsch & Maria Ferrari
- The TV Critic: "This was very enjoyable. The two plots were set up early on, both were clear and easy to get into with clear motivations for all involved. The Sheldon story played to his strengths. His inability to be subtle and hide his real motives make pranks ideal comedy... Leonard's story was really good. It was a simple moral dilemma that anyone and particularly guys could relate to... This was such a simple episode and it was really effective. It drove the plot while making use of the season and the characters."
- The A.V. Club gave this episode C
- IMDb user reviews
- Title Reference: Leonard describes his superpower as being a good guy and how it changes (fluctuates).
- Chuck Lorre's vanity card.
- This episode was watched by 14.54 million people with a rating of 4.6 (adults 18-49).
- This episode aired in Canada on October 27, 2011 with 3.751 million viewers and a weekly ranking of #1.
- In the United Kingdom, this episode aired on December 8, 2011 with 1.395 million total viewers and a weekly ranking of #7.
- In Australia, it aired on November 7, 2011 with 1.346 million viewers and a weekly ranking of #6.
- Episode Transcript 
- Leonard wears his white on green recycle logo shirt.
- Amy does not feature in this episode (whether mention, cameo or speaking role) This is the first of three episodes Mayim Bialik is absent from in the fifth season; the second is "The Transporter Malfunction" (S5E20), and the third is "The Hawking Excitation" (S5E21).
- The mask Leonard uses to frighten Sheldon is a mask of the character "Balok" from the Star Trek original series episode "The Corbomite Maneuver". The character was actually a mask or audio animatronic dummy used by a "not-so-scary" alien life form.
- Bernadette only appears in one scene of this episode and Penny only features in two scenes in this episode.
- Like Raj, Sheldon urinates himself, among other things, when he is scared, just as Raj voted. In "The Bozeman Reaction" (S3E13), he utters for the second time, "I am the master of my own bladder," as a frightened Sheldon crawls across a window ledge. The first mention in that episode is simply because he is too scared to go to the restroom, on the other hand.
- Sheldon aptly says, "It's not suspicious that I'm fixating; it's consistent with my personality." Leonard points this fact out in "The Infestation Hypothesis", revealing, "Sheldon, you do this all the time; you fixate on some crazy idea and then blow it way out of proportion."
- Leonard finally connects a beautiful girl who shares his interests and who could give Penny trouble.
- Alice is played by Courtney Ford, who is married to Brandon Routh, an actor known for his role as Superman in Superman Returns. Superman is Leonard's favorite superhero as seen in "The Big Bran Hypothesis" (S1E2), "The White Asparagus Triangulation" (S2E9), and "The Justice League Recombination" (S4E11). Alice even makes a reference to Superman: "I'm forbidden by my Kryptonian father to do so."
- As Leonard asks Sheldon what he is doing, Sheldon responds, "Science. You wouldn't understand." He similarly mocks Leonard in "The Monopolar Expedition" (S2E23) when he says, "Perhaps you mean a different thing than I do when you say science."
- Sheldon uses a screwdriver, but can't even open a tool box in "The Killer Robot Instability" (S2E12).
- Oddly, Sheldon does not say anything about Leonard sitting in his spot at the end of the episode; however, Leonard still has it coming when Sheldon scares him.
- Last appearance of Priya in the show.
- Fourth episode where Sheldon screams. The first was "The Nerdvana Annihilation" (S1E14), the second being "The Euclid Alternative" (S2E5), and the third episode was "The Bozeman Reaction" (S3E13).
- When the lights flicker near the beginning of the episode, captions on The Complete Fifth Season DVD say"[ENERGY CRACKLING]" rather than "[ELECTRICITY CRACKLING]".
- Alice is probably Penny's greatest rival since she is beautiful like her, but is interested in comic books unlike Penny.
- (Raj and Howard attempt to scare Sheldon, but he is unfazed.)
- Sheldon: Please, fright depends on an element of surprise. The simple fact is, because I am much smarter than you, and able to anticipate your actions, it is highly unlikely that you two rubes could ever surprise me.
- (Unnoticed by Sheldon, Leonard emerges from a closet wearing a mask of Balok from Star Trek.)
- Raj: He’s probably right.
- Howard: We can’t beat him. He’s just too smart.
- Sheldon: (dismissively) Gentlemen. (Turns and sees Leonard in the Balok mask; then screams and faints.)
- Howard: (as the trio survey an unconscious Sheldon) Who had money on faints?
- Raj: (disappointingly) I had pee his pants.
- Leonard: Hang on. (peers closely at Sheldon) Looks like everyone’s a winner.
- Sheldon: You think you've poked fun at a milquetoast academic. Well, you've forgotten one thing. I am also a son of the Lone Star State. I’m Texas through and through. And we know how to settle scores down there. If you doubt me, ask Mexico.
- Penny: It's a rough month when Halloween and PMS hit at the same time.
- Leonard: No, no, I messed up a little, you messed up a lot.
- Priya: Well it's not a competition!
- Leonard: Oh yeah it is, and you won.
- Sheldon: Bazinga, punk! Now we're even.
- Alice: I'm forbidden by my Kryptonian father to do so.
- Sheldon: I tried to scare an Indian with a snake. Come on, Cooper, you're better than this!
- Leonard: Damn it, I can’t. I can’t, I can’t do this.
- Alice: Uh, is it my tongue stud? ‘Cause if that freaks you out; you’re in for a real surprise later on.
- Leonard: No, no, no. I, I can’t do this. Believe me, I really want to.
- Alice: But?
- Leonard: But I kind of have a girlfriend.
- Alice: Are you kidding?
- Leonard: You’re cool with you and me just being friends, right?
- Alice: I don’t believe this.
- Leonard: Wait, I don’t, which part?
- Alice: I’m so stupid. I thought for once I’d met a good guy, but you’re just another jackass.
- Leonard: Oh, no, no, you have it wrong. No. I, I was going to be a jackass, but I stopped myself. I stayed a good guy, so, I’m gonna pass on the sex. But you should know, that’s not a comment on your hotness but on my goodness. That’s kind of my superpower. I’m, like, Captain Good Guy.
- Leonard: It's okay. Did the right thing. You idiot!
- Howard: Hey, Sheldon.
- Bernadette (as Mrs. Wolowitz): (out of vision) who is it?
- Sheldon: It’s me, Sheldon, Mrs. Wolowitz.
- Howard: That’s not my mom, it’s Bernadette.
- Sheldon: Really? That’s very unsettling.
- Bernadette: Hi, Sheldon.
- Sheldon: Hi.
- Howard: What’s up?
- Sheldon: It just occurred to me that I never formally congratulated you on your pending nuptials. So I hopped on the first bus and hightailed it down here to shake your hand. Put ‘er there, you old so-and-so.
- Howard: Well, I, I’m gonna see you at work in 12 hours, don’t you think it could have waited until then?
- Sheldon: Holy smoke, why didn’t I think of that? You’re a better man than I, Howard Wolowitz. You put ‘er there, you son of a gun!
- Howard: Whatever. (Takes his hand. Starts to be electrocuted) My… oh… it’s… (Clutches heart and collapses)
- Bernadette: Oh, my God, Howard! What did you do?
- Sheldon: It was a harmless Halloween prank. Look.
- Bernadette: Howard has a heart condition! You know that!
- Sheldon: Well, I thought he made that up. Isn’t hypochondria a common idiosyncrasy of Jewish people?
- Bernadette: This is adrenaline, we’re gonna have to inject it into his heart.
- Sheldon: We are?
- Bernadette: You are. I’m not strong enough to get it through his chest plate, and we’ve only got one shot.
- Sheldon: Oh, no! I can’t!
- Bernadette: Hurry! We’re running out of time!
- Sheldon: Okay.
- Bernadette: Just do it!
- Sheldon: Oh, God! One, two, three!
- Howard: Trick or treat, bubbeleh.
- Sheldon: What? No. You mean this was all a ruse? Oh, how could I be so stu… (puts hand to forehead. Electrocutes himself).
- ↑ The Big Bang Theory - The Good Guy Fluctuation (TV Episode 2011) - IMDb
- ↑ The TV Critic's Review
- ↑ The Big Bang Theory: “The Good Guy Fluctuation” - The A.V. Club
- ↑ Thursday Final Ratings: World Series Game 6 Finals + 'Big Bang,' 'Vampire Diaries,' 'Office,' 'Person,' Adjusted Up; 'Rules,' 'Secret Circle,' 'Whitney,' 'Prime Suspect' Adjusted Down - Zap2it
- ↑ Top Programs – Total Canada (English) October 24 - October 30, 2011 - BBM Canada
- ↑ BARB via Wikipedia
- ↑ Free to Air TV Ratings, Week 46 (November 6-12), 2011 - Throng.com.au
|Episodes | Season 5|