Didn’t you hate it when you got a card in your box that wasn’t signed? For the rest of the day you wondered who the card came from. Was it the little redhead girl that you had a crush on and she was too shy to sign her name? Or was it from the disgusting he-eats-his-own-boogers kid that was just too stupid to sign his name?
Oh, I almost forgot! You're probably wondering what the answer is to the Knock, knock joke. Are you ready? Here it is - "Sherwood be nice if you'd be my Valentine!"