The Big Bang Theory Episode 6.14 The Cooper/Kripke Inversion

Sheldon is outraged when he learns that the university is forcing him to work with Kripke on a potentially groundbreaking new project. His self-esteem takes a hit when he and Kripke exchange work and he discovers that Kripke's work is leaps and bounds ahead of his own. Fortunately, Kripke thinks Sheldon's work is suffering because he is constantly having sex with Amy, and Sheldon decides to go along with the lie to save face. Later, when Penny and Leonard confront Sheldon about it, he admits that he might actually sleep with Amy... one day. Meanwhile, Koothrappali and Wolowitz order personalized action figures in their likeness, but the figures they get look nothing like them at all. Determined to get their action figures, they decide to split the cost of a very expensive 3D printer to make their own figures. The printer works like a charm, but Bernadette gets upset when she learns how much Wolowitz spent and makes him get a refund.