A little boy is taking a bath with his grandma.  He points down and asks, "Grandma, what's that?"  She's embarrassed and says, "That's my beaver, now don't say anything more about it."  A couple nights later the boy is bathing with his mom.  He points down and says proudly, "Mom, I know what that is.  It's your beaver!"  "Where did you hear that?"  his mom asks.  "From Grandma," the boy replies.  "Only I think hers is dead because it's tongue was hangin out!"

That joke was wrong on so many levels.