"Suxor" is one of the more common examples of hacker slang (HaXor or leet speak). It is a negative adjective, and is a mangled version of the slang word "suck" (as in "this sucks!".) Occasionally, it may be used with a capital X in the centre.

It was possibly, many moons ago used in all seriousness by those who are totally 1337, usually 14 year old boys. Like most haXor, it's used now in an ironic fashion, often to lampoon the far too serious and far too geeky hacker stereotype. Slashdot, Fark and Everything2 are prime places to find the term in use.

It's usage is a bit peculiar - it being slang and ironically used slang at that - and is intentionally grammatically incorrect in most places. Grammar is obviously not something 14 year olds care about, grandad. It should be preceded with the other 1337 word "teh". Not "the", but "teh".

Examples of its use: "I is 1337. U is teh suxor". "Windows is teh suxor".

The opposite to this term is "roxor", presumably from the slang "to rock". If you are 1337, you are teh roxor.

Worryingly, I've used these terms several times in conversation in the real world. Fortunately, it's been during a conversation with fellow techies, so they get my meaning. Coz tehy is 31337.