It seems that there is a pattern in all friends series, in the fact that the middle episodes of the series are usually not as good as the first or the last ones . Series 5 is a similar case; of course one has to keep in mind that in Friends lack of hilarious situations is never the case. Episodes 13-16 revolve around small little everyday - life occurrences which are, as usual, a lot of laughs. But these episodes' role is to bring you through to the last series' episodes where every single situation practically goes out of hand. On the other hand, there is a key element here: the big revealing of Chandler and Monica's relationship in episode 14, which is something definitely not to be missed (After finding out, everyone decides to have a little fun with them and Phoebe's part is hilarious in this situation)!!! In conclusion, episodes 13-16 are the bridge that should lead you to the closing of series 5 and the beginning of series 6. In my opinion, although they are not the greatest episodes ever (still, they are a lot of fun), they are essential to the overall plot and you cannot really go without them.