Little Johnny learns to curse 

One day Billy and Johnny were sitting in the park wondering why grownups have so much fun cursing. 
Finally Johnny says to Billy, "Tommorow your gonna say 'hell' and I'll say 'ass' for the rest of the day." 
So the next morning their father calls them down for breakfast. 
"Billy, what do you want to eat?", their father asks. 
"Uhhh, what the hell, I'll have Froot Loops!", replies Billy. 
SMACK! Their father hits Billy right on the back of the head. 
So he turns to Johnny. 
"What do you want!", asks his father angrily. 
"You can bet your ass I'm not going to ask for Froot Loops!", he replies