Heres one I saw a while back:
Three turtles named Tom, ****, and Harry decide to go for a picnic. So they pack up a bunch of sandwiches and beer, and head out. Only problem is that the picnic site is ten miles away, so it takes them ten days to get there.
When they finally arrive, they set up the picnic, and Tom turns to **** and says "Okay, gimme the bottle opener."
"What?" says ****, "I didn't bring a bottle opener."
So Tom turns to Harry. "Did you bring a bottle opener?"
"No," says Harry, "I thought you brought it."
So after a few minutes of arguing, Tom and **** ask Harry if he'll go back to the house to get the bottle opener. "No way," says Harry. "Once I leave, you two are just going to eat all the sandwiches." Tom and **** swear on their lives that they won't touch the sandwiches until Harry returns. So Harry takes off, and Tom and **** wait.
Ten days go by. Tom and **** say to each other "Okay, he's back at the house by now, just ten more days until he gets back, and then it's sandwiches and beer!"
Ten more days go by, and Harry doesn't appear. Tom and **** start getting concerned. Harry should have been back by now-- it's been twenty days. But still they wait.
Ten more days go by, and still no Harry. **** turns to Tom and says "Hey man, it's been thirty days. He should have been back by now. Let's eat the damn sandwiches."
"No way," says Tom. "We swore on our lives that we wouldn't touch them until he got back. We're waiting."
So ten more days go by-- it's been forty days since Harry left. **** turns to Tom and says "C'mon, man, I'm starving. Let's eat."
"Well," says Tom, "tell you what. Let's open one sandwich, and split it, and we'll save the rest for when Harry gets back." So they open up one sandwich, tear it in half, and get ready to eat.
Just then, Harry pops up from behind a rock a few feet away, and shouts "MAN, I ****IN' KNEW IT!!! I'M NOT ****IN' GOING!!!"