The linear deliniation which defines the appropriateness of the age difference between a male and female in a relationship.
Half the males age + 7 = Creep Line. If it equals more = ok, less = creep
"Matty smutted Lasqueesha last night at the bar. He's 30 and she's only 21, that's totes below the Creep Line dude"
Matty: Dude, hit that ass up!
Tim: No way man, she's like 16, totally below the Creep Line!