Grenade Swarm (Verb) : To deliberately aim grenades at a single point from multiple players, so as to remove defenses from a long way away. Considered very bad manners, despite being a clever tactic.
It is often compared to camping and zerging, as both are considered weak strategies, while often being part of the game's design...
Base Defender: Haha, I am sniping you and you cannot... <BANG!> WTF?!?!? I'm dead! How'd I?!? You f*(!ing NOOBS, YOU GRENADE SWARMED ME!
Attacking Team: Oh, suck it up, you big camper!