Sheldon, Howard, and Leonard give a presentation about careers in science to a group of girls in junior high on The Big Bang Theory. "The Contractual Obligation Implementation" is the 18th episode of the shows sixth season.
Penny: Here's a question-- as an alien pretending to be human, are you planning to engage in any post-prom mating rituals with Amy? Sheldon: There are post-prom mating rituals? Penny: Not always. Unless your date drives a van with an air mattress, then always. Sheldon: Well, if it's part of the prom experience, then I'm open to it. Penny: You're kidding. Sheldon: I may be an alien, but I have urges.If Amy wants to copulate by firing her eggs into space, well, then, I will happily catch them with the reproductive sac on my upper flermin. I'm not the best at reading facial cues, but I can see that you're a little turned on.