The housewife answered a knock on the door and found a total stranger standing on the doorstep.
“Excuse me for disturbing you, ma’am, “he said politely, “but I pass your house every morning on my way to work, and I’ve noticed that every day you appear to be hitting your son on the head with a loaf of bread. “
“That’s right. “
“Every day you hit him on the head with a loaf of bread, and yet this morning you were beating him with a chocolate cake. “
“Well, today is his birthday. “
This joke is included in the Black Book of Jokes. You can order it from here.