Schoolboy

A young boy comes home from school and his mother says,

"What did you do today?"

To which the boy says, 

"Oh, the usual, I had a maths test, I got an A in spelling and I 
had sex with my English teacher."

The mother, aghast, doesn't know what to say! She stutters
and stammers and finally says 

"Go and tell your father what you just told me!"

The boy goes into see his father and moans, 

"Gee, mum is really mad."

"Why?" The Father asks.

"I just told her what I did in school today. I had a maths test, I 
got an A in spelling and I had sex with my English teacher."

Well the father is beside himself with joy. He gives his son 
a nudge and a wink and says

"Congratulations, you passed a milestone. I tell you what, let's go 
out and celebrate. We'll have some ice cream and then I'll buy you a 
new bike."

To which the boy replies, 

"The ice cream sounds great, but can we hold off on the bike a few
days, my arse is killing me."