This term is mostly used to describe the Claymore (Anti-Personnal Device) in the game Battlefield 2.
The words have been swaped from "Clay" to "Gey" because they require no skills to use and are spammed alots.
Guys 1: Hey dude! Cover me while ill plant a Geymore at their spawn.
Guys 2: Alright.
Guys 1: *Plants the Geymore"
Enemy : *Spawn* then gey owned in a sec by the Geymore leaving him no chance to survive.