frag \frag\ (fr[a^]g), v. t. [imp. & p. p. {fragged} (fr[a^]gd); p. pr. & vb. n. {fragging}.] [by shortening from fragmentation grenade; ca. 1965.] (Mil.) To assault, especially to kill or wound, with a fragmentation grenade. [Slang]
Note: This term became popularized when disaffected American troops serving in Vietnam were reported on occasion to kill unpopular commanders by the use of grenades. [PJC]
Others are more murky, such as porky (a lie), frag (a little bit) and brick (falsify evidence).