A lad comes home from school one day and his mum notices he's grinning from ear to ear
"What's the matter with you, you look like the cat that's got the cream?"
"Well mum" says the lad, "today I made love with my English teacher in the stock room".
The mother is furious and says "just wait till your father gets home!"
When the dad gets home he too acts furious but when the mother leaves the room he starts grinning too - proud as punch that his son has got a shag so early on.
"Son" he says, "today you did your old man proud - you've become a man, and as a treat I'm going to take you for a pint then we'll go and buy that mountain bike you've had your eye on".
"That sounds great dad" says the lad "but can I have a skateboard instead - my arse is killing me..."