Del Big Bang 1x3 - La Teoria

It sounds like you’re referring to of the TV show The Big Bang Theory . That episode is titled "The Fuzzy Boots Corollary" .

Sheldon is trying to win a "Fuzzy Boots" doll from a claw machine at the Cheesecake Factory to complete a set for his mother, convinced it involves a precise mathematical formula. He fails spectacularly until Penny (who feels bad for Leonard) wins it on her first try using pure intuition.

Leonard is depressed after learning that Penny is seeing someone (a handsome, muscular guy named Eric from her gym). Howard suggests Leonard use "corollary" thinking (a proposition that follows from one already proven) — basically, if you ask enough women out, you’ll eventually get a yes. Leonard tries but fails with several women.