A 12 year old boy comes home from school and says to his mother "I had sex with my french teacher today". His mother is dumbfounded and sends him to his father for a stern telling-off.
So the boy tells his father the same thing. Hearing this the father beams with pride and says "Well done son. I think you're now old enough to ride your big brother's bike". "I can't" said the boy "my butt hurts too much".