The 'post frag t-bag' is a variation on the physically expressed gaming insult known as t-bagging. The phrase refers to performing the t-bag action on a recently killed enemy or group of enemies that was specifically defeated by the use of fragmentation grenade. Due to the large splash damage of fragmentation grenades, it is not uncommon for multiple targets to be killed, and therefor multiple players being 'post frag t-bagged'

When you eat dirt for the first time and leave your family to build a shack in the woods