Noun derived from the words cheat and noob. Holds negative connotation.
Choob: a noob who single-mindedly hones and utilizes skills very heavily dependent upon unsportsmanlike tactics (usually exploiting "overpowered" features included legitimately in a game) in order to appear proficient at a game.
Similar variant: chewb
Player 1: "Use something other than an AWP for once in your life, you choob!"
Player 2: "You're just mad that you got pwnt by my 1337 skillz."