1650s, "anything which bangs," in any sense, agent noun from bang (v.). British English slang for "a sausage," by 1919, perhaps is from a sense of "a bludgeon," though this is recorded only in U.S. slang. Bangster was a 17c. word for "muscular bully."

"hair cut straight across so as to form a fringe over the forehead," 1878 (in singular, bang), American English, attested from 1832 of horses (bang-tail), perhaps from notion of abruptness (as in bang off "immediately, without delay," though this expression is attested only from 1886). See bang.

1953, "group sex" (especially many men on one woman or girl, regardless of consent), from gang + bang (v.) in its slang, "perform sexual intercourse" sense. Earlier was gang-shag (1927). Sense of "participate in a street gang" is by 1968. Related: Gang-banger; gang-banging.

"devotee of heavy metal music," 1984, from head (n.) + agent noun from bang (v.).

also whiz-bang, whizz-bang, 1915, originally a soldier's name for a type of German artillery shell in World War I, so called by the Allied troops in reference to its characteristic sound. From whizz + bang (v.).