Heres one I made up in school:
Ok, so theres 3 people. A blonde, brunette, and a red head. They were in heaven and god made them a deal. He said that there is 1000 stairs, that whenever you touch them it says a joke, and if you made it to the top without laughing, you wouldn't have to go to hell and could stay in heaven. So, the red head went up 10 stairs and laughed. The brunette went up 200 stairs, then laughed. The blonde made it up to the 999th stair then laughed, before the joke even played. God then asked her what she was laughing at, and she said "What are you talking about? I just got the first joke!".
When you get this, you will most likely laugh. :P