Chandler (Matthew Perry) and Monica (Courteney Cox) have a date on the anniversary of their relationship, but the event is spoiled by a blast from the past, courtesy of the gone-but-not-forgotten Janice. Meanwhile, Joey (Matt LeBlanc) must find somebody to pose as his "twin" in a medical study, so that he can raise money for some new publicity photos. And Rachel (Jennifer Aniston) and Phoebe (Lisa Kudrow) take classes in self-defense -- and are given a free demonstration in "Unagi." ~ Rovi