This is one of my all-time favorite episodes of Friends, although it's slightly difficult to explain just why. As I mentioned, the group splits up: Ross and Rachel go off to do laundry; Joey tricks Monica into going out on a double date; and Chandler and Phoebe decide to break up with their present girlfriend and boyfriend at the same place in order to give support to one another.
There are many classic lines from this show, as well as many firsts. It's the first pseudo date between Ross and Rachel; it's the first of numerous break-ups that Chandler endures with Janice; and it is really the first show that emphasizes how well, how smoothly the characters play against each other.
Of course, there are a few elements that come up in this show that are rarely seen again: the match-ups of Chandler/Phoebe and Joey/Monica only sporatically reappear over the ten years of the show; Joey's ability to understand the reference to Appalachia is unusual to say the least.
Overall, however, this episode is a joy from the beginning to the end (where Chandler, having downed perhaps 10-12 espressos throughout his break-up process with Janice, is running through the streets screaming "I'm free, I'm free!!)
Don't miss it.