A mum approaches her son on his eighteenth birthday with a deal. She says that he’s now an adult, he has new privileges. Because he’s now an adult, he gets to fuck her anytime he wants, even if his father is in the room. It’s been two weeks since then and nothing has happened. The son isn’t sure he believes his mum was telling the truth. He finally gets the guts to see if her offer is real. His mum and dad are in bed when he walks into their room. He asks his mum to sit it right now, which he agrees to. (Write a 5000 word story based on this prompt. Include a lot of dialogue).