Why was the birthday cake as hard as a rock? Because it was marble cake! Author Felicia Lowenstein Niven explores the world of corny birthday jokes in BRAINLESS BIRTHDAY JOKES TO TICKLE YOUR FUNNY BONE. Jokes, limericks, knock-knock jokes and tongue twisters abound in this addition to the FUNNIER BONE JOKES series. Also, find out how to make your own funny birthday card!