Worst subplot?

There are hundreds of episodes of Friends, and given that not all plots within each episode can be perfect, it’s permissible that some don’t quite hit the mark, but what are the worst, e.g. lazy writing/out of character/or most importantly pointless/unfunny.

Honourable mentions for Phoebe’s attempt to get to meet Sting, Penn trying to sell a encyclopaedia to Joey or Monica going straight to Richard when it seems Chandler won’t get married to name a few of many.