5x11 "The One with All the Resolutions"

The gang makes New Year's resolutions: Chandler cannot make fun of his friends, Rachel will gossip less, Ross will do something new daily, Joey will learn to play the guitar, Phoebe will pilot a commercial jet and Monica resolves to take more pictures of all the friends together. However Rachel's resolution is put to the test when she overhears Monica and Chandler talks and learns of their relationship. Soon she and Joey find out the other knows, much to their mutual relief since they can now talk about it. Phoebe tries to teach Joey how to play the guitar, however her teaching method is so unorthodox (not even letting him hold the guitar) that he soon starts looking for another teacher. Ross decides to wear leather pants to a date but this backfires as the pants shrink and he finds himself unable to put them back on during a date after he has gone to the bathroom.