I have seen this episode so many times but it always cracks me up. There are three all very excellent storylines running throughout it:
Firstly the one with Joey on Pyramid is hilarious. You realise just how stupid he is (if you didn't already know) but it's so funny. When he said "...why would there be a ghost in my fridge?" I cracked up. And then he has a moment of triumph at the end where he almost wins the jackpot and I was with him all the way! Joey is really a loveable, sweet and innocent person in many ways.
Secondly there's probably the main storyline of Phoebe's bachelorette party, which is probably the least funny in my opinion, but still good. With guest star Danny Devito playing an aged stripper, the three girls are at first repulsed by him but eventually let him do his last dance for them when he breaks down. Features one of my favourite songs ever Tainted Love!
But my favourite storyline has to be the flashback one with Ross and Chandler at college. You learn that Monica's first kiss was actually with Ross and that Chandler kissed Rachel. Utterly hilarious and just amazing! I love finding out bits about the characters pasts and this was incredibly well scripted flicking between the guys at their college reunion.
Overall this episode is very well written, very funny and just very enjoyable to watch! Excellent.