Three classic ones from World of Warcrack that always made me laugh:
1) A guy walked up to me and said: 'I'm a tepee, I'm a wigwam, I'm a tepee, I'm a wigwam!'
I said: 'Relax man, you're too tense (tents).
2) A duck walked into an apothecary and said 'Give me some chapstick, and put it on my bill.
and finally a spoof on LoTR:
3) "So, I have this idea for a great movie. It's about two gnomes who find a bracelet of power, and they have to take it to the Burning Steppes and cast it into the Cauldron. They form the Brotherhood of the Bracele, and along the way they're trailed by a murloc named Gottom, who's obsessed with the bracelet, and nine bracelet bogeymen.
It could be a three-parter, called 'Ruler of the Bracelet'. The first part would be called 'The Brotherhood of the Bracelet', followed by 'A Couple of Towers', with the climactic ending called 'Hey, the King's Back!'"