: Leonard sees Penny through a doorway and, on a whim, asks her to dinner. She accepts, leading to a romantic evening that starts well but quickly devolves into an argument about the "beta test" of their relationship.
: Much of the episode's middle section is revealed to be a hypothetical scenario imagined by Leonard as he stands in the hallway, weighing the pros and cons of asking her out. Episode 13: The Recombination Hypothesis
is the 13th episode of the fifth season of The Big Bang Theory and serves as the landmark 100th episode of the series. Episode Overview : Leonard sees Penny through a doorway and,