Remember this is not one of my jokes... and unfortunately I don't have a reference to who it has been written by.
There were two young brothers talking in their backyard waiting for their mother to make them lunch. Billy: "I'm getting pretty old now, I think I can start cursing." Bobby: "Oh yeah?" Billy: "Yeah, I think I am going to start saying 'damn' whenever I feel like it." Bobby: "You know what?" Billy: "What?" Bobby: "I think I am getting pretty old, I'm going to start cursing too." Billy: "Oh yeah? what are you going to say?" Bobby: "I'm going to say 'ass'". Then their mother calls them in for lunch. The mother asks the four year old: "What do you want for lunch?" Billy: "Oh, damn, I think I'll have some Spaghetti-O's" At this point, the mother was aghast. She quickly took the four year old by the ear to the bathroom, washed his mouth out with soap, spanked him and put him in his room and slammed the door. She returned to the kitchen and asked the three year old: "What do you want for lunch?" Bobby: "I don't know mom, but you can bet your ass it won't be Spaghetti-O's!'