The Big Bang TheorySeries 5 Episode 13: The Recombination Hypothesis
In the 100th episode of the popular US sitcom, Leonard decides to ask Penny out on a date, and they both agree to give their relationship another chance. They argue over dinner and remember why things didn't work out between them in the first place, but end up sleeping together anyway. Later they agree to continue seeing each other secretly, on the condition that they act like friends when everyone else is around.
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