1337hax

1337hax is a term that means you did something impossible that is amazing. So it's actually hax, but so 1337 that noone cares.

Me shooting noob through a wall
Noob: 1337hax!

1337hax by DC Gold March 29, 2009

1337 hax 

1337 hax means literally "Leet hacks" or "Powerful/Uber hacks"

Basically, a 1337 h4xor uses 1337 hax.
World of Warcraft Term (common).
If somebody is using speed hacks or any other hacks in WoW, people say..."Dude, 1337 hax"

"Zomg, 1337 hax brah"
"rofl, 1337haxxx"

1337 hax by Leeeeeeeeeroooooooooooy Jenkins November 9, 2007