Little billy...

[Jared]

SO one day little billy is upstairs in his room pleasuring himself, when all of a sudden his mother walks in.

She exclaims! don't you know that You'll go blind doing that?

To which little billy says, well momma can i just do it till I need glasses?

[Sock]

SO one day little billy is upstairs in his room pleasuring himself, when all of a sudden his father walks in.

He exclaims! don't you know that You'll go blind doing that?

To which little billy says, Over here Dad!!

Old and a bit corny but still good.

Sock

[Iroquois]

Ok here's one.

One day little Billy's mom is cleaning his room and discovers a bondism magazine under his bed.
She waits until his father gets home. She exclaimes "look at what our little Billy has been reading, what are we going to do about this!"
To which the father replies "Well you better not spank him."  ;D