When Sheldon formally charges Leonard with breaching the roommate agreement by taking a shower with Priya in the apartment bathroom when Sheldon had a "call of nature" (constituting what Sheldon considers an emergency), Priya, a lawyer, decides to intervene on Leonard's behalf on the case. When Priya (and thus Leonard) win this round, they decide to test other sections of the agreement in actual practice. When Sheldon can't handle what's going on with Priya and Leonard openly mocking the sanctity of the agreement, he turns to Penny, who in turn invites Sheldon on her girls night out with Bernadette and Amy. Sheldon accepts Penny's invitation only on the promise by Penny that some Priya bashing will occur on their outing. Their outing takes them to a ballroom dance club, where Sheldon starts to see a different side of Amy, one being influenced by Penny and alcohol consumption...
Written by Huggo
Incorrectly regarded as goofs:
While at the bar with Penny, Amy and Bernadette, Sheldon is asked if he has ever kissed a woman. He states that other than family he hasn't, yet in 'The Maternal Congruence' he is kissed by Leonard's drunk mother. Given Sheldon's literal-mindedness he wasn't lying (or ignoring continuity), since he wasn't the one initiating this kiss.
See more »