The Vengeance Formulation

Summary
Wolowitz's new girlfriend, Bernadette, asks him where their relationship is going after their third date. He avoids her for a week, thinking about whether he should "settle" for her or hold out for the impossible (a hot girl from a sci-fi series being interested in him). After a dream in his tub involving a romantic evening turned lecture from Katee Sackhoff, he decides that he should stick with reality. He proposes to Bernadette at the Cheesecake Factory, gets rejected, and then sings her his version of the song "Bernadette" (by the Four Tops) in order to win back her affections, in which he becomes successful when she declares it as the most romantic thing anyone has ever done for her.

Meanwhile, Barry Kripke embarrasses Sheldon severely on the National Public Radio talk show Science Friday (by filling Sheldon's office with helium so that his voice is high pitched). While at first pouting and announcing defeat, Leonard and Raj, (originally just tormenting him), convince Sheldon to fight back. Sheldon vows to destroy Kripke, by using an elaborate trap in which after a chemical reaction set off by a human presence in Kripke's office, foam will fall through the ceiling into Kripke's office, effectively covering him in foam. However, the trick backfires on him when the Caltech president and board of directers get hit by his prank as well thanks to Sheldon's lack of an "abort" system. And to add insult to injury, Sheldon had a pre-recorded video stating that he sent the taped trick to YouTube, and proclaiming himself the mastermind. But Leonard and Raj share the consequence when Sheldon lastly gives them credit for the scheme.

Title reference: Sheldon's revenge against Kripke by dropping a chemical foam from the ceiling in Kripke's lab.