1.) A personal brand in the form of an 8 superimposed on an X, commonly found on Teenage Mutant Ninja Turtle paraphernalia.

2.) A term used to describe an object or situation in reference to the behaviour and/or character of the owner of the brand X8 (see 1).
1.) "TMNT! Ohwaht, X8 man! D.F. Tree!"
2.) "Who X8'd the driver's seat?"
by The winner is...Ratbug! July 8, 2005