A grenade launcher usually attached to the bottom of an M-16 or M4 assault rifle. More commonly known to Soldier of Fortune 2 players as the n00b cannon due to the fact it is easy to use and can frag a player in one shot, hence it is a favourite among n00bs.
Shiiiiiit! I just got fragged by that n00b and his M203 n00b cannon.
Prices shown in USD.