derived from the roman numerals xxx, meaning both 30 and porn. came around in the 21st century when members of the GPK needed code words to get past their parents. also makes it more comfortable to talk about porn.
Alex: Hey, dudes, i found some sick ass 30 last night.
Dan: Aww no way. i got grounded from the computer cuz my parents found out about my 30
Steve: Ur a dumbshit, 30 rocks.
Giussepe: I LOVE 30!