A person with an IQ under 70 who happens to play video games non-competitively. Typically characterized by phrases such as "john smith is cheating", "wtf how did you know i was sitting there around that corner, i had only killed 8 people right in front of you!", "quick give our sniper some cover, throw a smoke in front of him!" "you're aimbotting! you missed me twice and then hit me on the third shot, but i wasn't standing still so you must be aimbotting!" "you have more kills than deaths, you must be cheating!" "I have 14 kills and 58 deaths, but i have 15 objectives, so you're bad!"
The vast majority of server admins are pubbers and will ban known competitive players on sight, as well as anyone who's playstyle coincides with that of a competitive player.
Not to be confused with a recreational gamer, who may actually be semi-decent and make slightly more logical moves.
"man i was pubbing the other day and some 12 year old pubber admin banned me for cheating cause i was 52 and 3 with a sniper rifle, what a dick"
"haha i was wrecking this pubber so bad he actually started crying over the mic"
"wow are you really proned under a table with a sniper rifle watching a half inch x half inch section of your screen...what a pubber"