Friends Season 4 Episode 4 : The One With The Ballroom Dancing
Joey helps the apartment supervisor Treegor with his ballroom dancing skills in order to help Monica and Rachel keep their illegal apartment. Chandler wants to quit the gym, but can't because of the attractive staff. Ross, originally to help Chandler quit, ends up with a gym membership when they leave. Their later plan is to cut the gym from their financial source, so they attempt to quit their bank but because of the attractive female staff there, they end up with a joint-checking account.