I need some clean jokes that high schoolers would find amusing.?

I am a high school teacher, and I post a joke/riddle of the day, every morning. I am in need of some funny but clean jokes -- preferably short. The board I post them on isn't that big. I like riddles that make them think.

I need some clean jokes that high schoolers would find amusing.?-Myspace pictures

what did the fish say when it hit the wall? Dam.

Brothers and sisters I have none, but that man's father is my father's son. Who is that man? (That man is the speaker's own son)

I need some clean jokes that high schoolers would find amusing.?

-(Myspace images myspace.com)

I have a good riddle. Imagine that when u die u fall into a place, before salvation or damnation, that contains two doors. One goes to salvation and the other to damnation. There is also two guys, who do not know u. One of them ALWAYS tells the truth, who wants u to be saved, and the other ALWAYS lies about everything, and wants u to be condemned. U can ask one question to each one of them. What question would u ask so u can go to salvation? (U don't know which door is which and u don't know which man tells the truth) It's a hard riddle, but it's do-able. Think about it..i'll tell u the answer later if u cannot get it and want to use it in your class.

The question is Which door the other guy will say is the door of salvation? The guy saying the truth will say that the lair will tell u that the door of damnation is the door of salvation and the lair will say that the guy saying the truth will say that the door of damnation is the door of salvation, since he always lies.. now u know which door to take :)
You walk into a cabin. All you have on you are matches. In the cabin there is a candle, a lantern, and a fireplace. What do you light first?

The matches
what word becomes shorter when u add letters?????....the word short.....im not a teacher but i love it.
What did the number zero say to the number eight?

Hey, nice belt!
Get political cartoons, or cartoons from the New Yorker, and have them tell you why it's supposed to be funny. Every once in awhile, mix it up with a The Far Side cartoon.