derpcannon
A large-caliber, short-barreled firearm (by comparison to others used in similar ways) meant for creating carnage at spitting range and virtually useless at longer ranges. Examples include shotguns, most submachine guns, and on AFVs, a direct-fire mortar or a howitzer/gun (as opposed to the typical rifle or smoothbore gun).
Your rifle makes holes in things at long ranges where my derpcannon can't hit them, but my derpcannon utterly destroys them.