Johnny got into an embarrassing situation at a swingers’ party.
He snuck up behind an older lady, started fucking her from behind then looked up and suddenly realised that the guy at the other end of the spitroast, getting a blowjob, was his dad.
Johnny said, “After 30 years of marriage I can’t believe you’re being unfaithful to mum. “
His father said, “No, I’m not. “
This joke is included in the Black Book of Jokes. You can order it from here.