The two best jokes I know: The Six Day Camel and The Bus Full of Nuns

The Six Day Camel
A man on the edge of the Sahara desert has to get to a city 6 days away across the desert. He goes to the camel dealer and asks if he has any camels that can make it that far. The camel dealer says, "Yes, I have two six day camels." The man selects the best looking one and buys it. As he leaves, the dealer calls out "Make sure you fill him all the way up!"
The man takes the camel to the river and lets the camel drink until he can't drink anymore. Then he sets out across the desert. After three days, the camel dies of thirst. The man could have gone either way, but he was really pissed at the camel dealer, so he walked back the way he came, barely surviving the journey. He stomps up to the camel dealer and yells, "You son of a bitch! I paid for a six day camel, and you sold me one that only lasted three days!" The camel dealer says, "No, that was a six day camel! You must not have filled him up all the way!" The man says, "I let him drink until he could not drink any more! He was full!" The dealer says, "OK, I think I see the problem. Come to the river with me and I will show you how to fill a six day camel."
So the dealer gets the other six day camel and they go down to the river. The dealer leads the camel to the water and lets him drink his fill. Just before the camel is done drinking, he sneaks behind the camel and slams the camel's nuts between two rocks. The camel goes [at this point I have to explain this is a verbal joke, there is a critical sound effect. Make a surprised groan, but instead of pushing air out past your vocal cords, suck air in as you make the sound. Try it now so you get it.] "OOOOOH"
[at this point people laugh and think the joke is over].
The man says, "Good God! Doesn't that hurt?" The dealer says, "Not unless you get your fingers between the rocks."

The Bus Full of Nuns
A bus full of nuns is on its way to Rome to meet the Pope. A tire blows out and the bus veers off a cliff and falls 500 feet, killing all the nuns instantly. The nuns wake up and they are in a line in front of Saint Peter's Gate. The gates are closed, and Saint Peter is standing before the gate. The first nun steps up to Saint Peter and says, "I have lived a life devoted to God and I have not sinned. Let me in!" Saint Peter replies, "We have had some sinners dressing up in nun costumes before committing suicide, so you need to pass a test before entering." The nun says, "OK, go ahead." Saint Peter asks, "What was the name of the first man in the Garden of Eden?" The nun answers, "That is easy! It was Adam!" BING, a bell goes off, the gates swing open, the nun marches in, and the gates close. The second nun steps up. Saint Peter asks, "What was the name of the first woman in the Garden of Eden?" The nun answers, "That is easy! Her name was Eve!" BING, a bell goes off, the gates swing open, the nun marches in, and the gates close. The third nun steps up. Saint Peter asks, "What were the first words Eve said to Adam in the Garden of Eden?" The third nun is stunned. She scratches her head, screws up her eyes, then says "Jesus! That is a hard one!" BING, a bell goes off, the gates swing open, the nun marches in....