Short for the American musical duo "Twenty one pilots" or "twenty øne piløts"
See what they did there with the 0 in the middle, it's pretty entertaining.
Dude 1: Hey do you listen to t0p?
Dude 2: Haha, that's agreat joke, tell me more of that joke.
The act of becoming an absolute madlad/madladette. A T0P-tier legend sitting at the T0P 0' ya best-list!
Dude 1: "Damn Dude 2, someone said I'm T0P-ended, tf that mean?"
Dude 2: "Shiii homie!! That's fokken sick! You gotta be a fokken real one eh, to be T0P-ended is a rarehonor!"