Bob, Fred and Jim are walking back from work one day, when they come accross a monster
The monster said if your ..... dont add up to 21 Inches im going to eat you all,
So Bob pulled it out, it was ten inches
Then Fred pulled it out, it was ten inches
They both looked at Jim worryingly but he pulled it out and it was 1 inch
So because it added up to 21 inches the monster, let them go.
After the monster left Jim said to Bob and Fred 'Thank god i had a hard on' lol