Raj's parents set him up on a blind date and he fears he won’t be able to talk to her. Penny needs to practice her bartender skills for work and once Raj drinks alcohol, he finds that he can talk to girls.
Raj's parents, Dr. V. M. Koothrappali and Mrs. Koothrappali, have just got broadband and are checking up on their son via Video Chat. They then announce that they have set up Raj and Lalita Gupta on a date. Raj is outraged at their meddling.
The next day, Raj barges in and announces he is screwed and explains that Lalita has left him a message and is interested in meeting him. Since Raj can't talk to women, Howard "helps" him set up a date with her, though Raj told him not to. Penny comes in and announces that the Cheesecake Factory has given her a barkeeper shift and she would like to practice mixing cocktails with them. The gang goes to Penny's and all have a drink, except for Sheldon who asks for a "rum and Coke" without the rum. After sipping his drink, Raj speaks to Penny to everyone's surprise including Raj.
Soon they figure out he is able to surpass his selective mutism by consuming alcohol. On the date Raj is drunk, acts extremely obnoxious and his actions are putting off Lalita. Sheldon arrives and upon seeing Lalita, he gets excited as she deeply resembles Princess Panchali from an India|Indian folktale book ("The Princess & the Monkey") which his mother used to read for him when he was sick. Raj introduces Lalita to the gang and Sheldon starts reciting the lines from "The Princess & the Monkey" book, which Lalita finds flattering. Raj gets defensive and orders Sheldon to stay away from his future wife. It's then that Lalita reveals that despite what both their parents wanted, she has no intention of marrying Raj and just came on the date to get them off her case. She then invites Sheldon to dinner, leaving everyone dumbfounded. Sheldon has no idea that he just stole Raj's date.
Later, Raj informs his parents he struck out with Lalita because of Sheldon. This statement ultimately backfires when Sheldon reveals to them that Raj was drunk and obnoxious on his date. When Leonard later asks Sheldon if he was going to see Lalita again, he asks why since he already has a dentist.
Later Sheldon is singing "To Life" (L'Chaim) from "Fiddler on the Roof" at The Cheesecake Factory. Leonard is surprised and Penny explains she put alcohol into his rum and Coke (which Sheldon specifically asked to be alcohol free or virgin). Penny explained that the guys do their experiments and she does hers.
- Guest starring:
- Teleplay: Robert Cohen & Lee Aronsohn
- Story: David Goetsch & Steven Molaro
- "I don’t think the major problem here is the racial humor. The problem is that the episode doesn't develop Rajesh’s character well. He gets drunk and ruins a date which he didn't really want to be on. It doesn't say much about him and isn't funny enough to compensate for the lack of progress in the plot." - The TV Critic's Review
- IMDb user reviews
- Title Reference: Penny practices mixing cocktails and mixes a Grasshopper for Raj which has unique effects.
- With 9.32 million viewers, The Grasshopper Experiment was the third most watched episode in the first season.
- Chuck Lorre's vanity card 
- This episode was watched by 9.32 million people with a rating of 3.8 (adults 18-49).
- Episode transcript .
Sheldon wears four t-shirts this episode, starting with "Aquaman Rising" on a grey tee. At Penny's, he's seen in an aqua striped tee (discontinued at Urban Outfitters). As Sheldon is making the call to cancel his memberships, he's seen again in the Rainbow Bolts tee, sometimes found at RedBubble.com Finally, as Sheldon visits the Cheesecake Factory and sings, he can be seen in his Flash Jersey tee.
Leonard wears a red periodic table shirt , the "Fly Lower" shirt from Urban Outfitters (looks like a tree with root system - it's discontinued) and at the end the black "Out of This World" galaxy shirt. Howard wears a Superman belt buckle and a Batman belt buckle.
- Multiple new items in this episode:
- 3-D Space Navigator wireless mouse for notebooks on Sheldon's desk
- Silver Mesh Pencil Cube by Design Ideas, on Sheldon's desk
- Mini-Robosapien, on the bookshelf by the front door.
- McCormick Spice Rack with spices in the kitchen to the left of the stove
- Parasaurolophus dinosaur figure by YTC, on top of the card file
- City of Heroes game, on the table by the alcove (by the Halo helmet).
- This is the first time Raj speaks to a woman with the aid of alcohol, a running gag in the series,
- This is the first time Raj speaks to Penny.
- This is the first appearance of Raj's parents, Dr. V.M. Koothrappali and Mrs. Koothrappali in the series.
- This is the first time Sheldon is drunk in the series.
- Regarding Raj, Howard says to Leonard, "No, no, let’s see how long it takes him." In "The Jiminy Conjecture" (S3E2), in reference to Sheldon, Howard similarly states to Raj, "Uh, no, no, no, don’t tell him, let’s see if he can figure it out."
- This is the first appearance of Penny as bartender at The Cheesecake Factory which are in frequent.
- Grasshoppers would become Raj's signature drink, as seen in “The Griffin Equivalency" (S2E4), "The Herb Garden Germination" (S4E22) and "The Stag Convergence" (S5E20). He almost orders one in "The Hofstadter Isotope" (S2E20), but Howard stops him from doing so because it's not a "manly" drink.
- The final Big Bang Theory episode to air before the 2007-2008 Writers Guild of America strike, which put a hiatus on television production for three to four months.
- Howard mentions that at Disneyland people can hire Snow White to come to their house. In "The Contractual Obligation Implementation" (S6E18), Amy goes to Disneyland with Penny and Bernadette and dresses up as Snow White.
- Leonard says to Sheldon "I wonder who's gonna tell his parents they're not having grandchildren." Sheldon's father died when he was fourteen and this had already been mentioned, so Leonard should have just said "I wonder who's gonna tell his mother she's not having grandchildren." This could also just be because he was referencing what Raj said to Sheldon earlier in the scene saying "Tell my parents why they won't have any grandchildren!"
- According to the now defunct website Bubblews.com, the episode was originally titled "The Slippery-Nipple Effect".
- (Penny is practicing mixing drinks for the guys in her apartment.)
- Penny: Sheldon, what are you gonna have?
- Sheldon: I'll have a Diet Coke.
- Penny: OK, can you please order a cocktail? I need to practice mixing drinks.
- Sheldon: Fine, I'll have a Virgin Cuba Libre.
- Penny: That's, um, Rum and Coke without the rum.
- Sheldon: Yes.
- Penny: So Coke.
- Sheldon: Yes. And would you make it diet?
- Penny: There's a can in the fridge.
- Sheldon: A Cuba Libre traditionally comes in a tall glass with a lime wedge.
- Penny: (sarcastically) Then swim to Cuba.
- Sheldon: Bartenders are supposed to have people skills.
- Sheldon is drunk and singing "L'Chaim" on the piano at Penny's bar.
- Leonard: I don't believe it. What's gotten into him?
- Penny: Oh, maybe a couple of virgin Cuba Libres that turned out to be kinda slutty. (holds a bottle of alcohol up to Leonard)
- Leonard: (smiling) You didn't.
- Penny: Hey, you do your experiments, I do mine.
- Raj: I can't believe I'm sitting here next to little Lalita Gupta!
- Lalita: Well, you are...
- Raj: Little Lalita...That's kinda fun to say. (Chants Little Lalita three times) You should try it!
- Lalita: No, its okay....
- (Raj sips his Grasshopper)
- Raj: You have lost so much weight! It must have been so hard for you because you were so, so fat! You remember?
- Lalita: Yeah...
- Raj: Of course you do! Who could forget being that fat!?
- Raj: Back off, Sheldon.
- Sheldon: What?
- Raj: If you do not stop hitting on my lady you will feel the full extent of my wrath.
- Sheldon: I’m not hitting on her.
- Lalita: And I am not your lady.
- Howard: And you have no wrath.
- Raj: You are my lady. Our parents said so. We are for all intents and purposes one hundred percent hooked up.
- Lalita: Okay, let’s get something straight here. The only reason I came tonight was to get my parents off my case, I certainly don’t need to be getting this old world crap from you.
- Sheldon: Exactly the kind of spirit with which Princess Punchali led the monkeys to freedom.
- Raj: Oh, screw Princess Punchali.
- Lalita: Hey, you can’t talk to me like that.
- Raj: But you’re not Princess Punchali.
- Sheldon: Luckily for you, she could have you beheaded.
- Raj: Can you believe how pushy she is?
- Leonard: So don't call her.
- Raj: If I don't call her, I won't hear the end of my parents.
- Leonard: So call her.
- Raj: How could I call her? You know I can't talk to women.
- Leonard: I'm done. Anybody else?
- Howard: Give me the phone.
- Raj: Why?
- Howard: Just give it to me. (Dials)
- Raj: What are you doing?
- Howard: Don't worry. You'll thank me. (imitating Raj) Hello, Lalita, Raj Koothrappali. (Raj starts to chase Howard across the room.) Yes, it is good to talk to you too. So, what are you wearing? Oh, not important, so, anyhow, when would you like to meet? Friday works for me. And I call you with the time and place, but in the meantime, keep it real, babe. (In his own voice) You may now thank me.
- Raj: For what, making me sound like a Simpsons character?