A young boy of 12 walks into his parents bedroom one night to see his mum and dad "doing it" on the bed. His dad laughs, turns round throws a pillow at him and tells him to get out.

The next day, the dad goes into the boys bedroom only to find him bending his nan over the desk and giving her one. Mortified, the dad shouts "WHAT THE HELL ARE YOU DOING?!?!?"

The boy turns round with a smile on his face and says "AHHH not so funny when its your mum is it!!!"