April 23rd, 2014 at 8:04 PM
I made my username about 10 years or so ago, it was my gamer name in call of duty and world of warcraft. The "grim" part of the name comes from the idea of the grim reaper - the main aim of call of duty and world of warcraft being to kill the enemy, and the "pus" sub-fix adds an element of disgustingness or slimeyness. My friends at school started calling me this name too which was rather amusing