sxu is the opposite of sux, so it means you totally pwn people.
omfg! that 1337 guy sxu!
by UndeadChocobo January 24, 2005
When somebody gets owned or is just a retard named timmy. Sxu can be used in every sentence.
omfg mothball! u sxu!
by Toofy January 13, 2005