Chandler mentions that the only true Famous Joey is Joey Buttafuco who had an affair with a woman 18 years younger than him named Amy Fisher who ended up shooting his wife clear in the face. Which is why Joey says "Ya he really hurt us".
Monica mentions she is uncomfortable picking out other people's sex clothes (when Rachel asks what lingerie to wear for her date with Joshua). She is okay with asking others to do the same though. In season 8, the one with the birthing video, Monica asks Phoebe - but is intercepted by Ross.