The rule/man law that states that in order for a man to lose his virginity, the person he has sex with must be at least a 5 out of 10.
He got laid for the first time, but considering the chick was a 3, it doesn't count, violating The 5 Rule
There's at least 5 girls you would have sex with in a room. Not date or take home to mom, just 5 girls that if it came down to it, or a lot of booze clouded your judgement, you would.
"Dude I walked into class and the 5 rule applies!"