Also, knock or lick the hell or living daylights or shit or stuffing or tar out of. Administer a merciless beating to; also, defeat soundly. For example, The coach said he'd like to beat the living daylights out of the vandals who damaged the gym floor, or Bob knocked the stuffing out of that bully, or He swore he'd beat the tar out of anyone who tried to stop him. These colloquial phrases nearly always denote a physical attack. In the first, daylights originally (1700) meant “the eyes” and later was extended to any vital (living) body organ. Thus Henry Fielding wrote, in Amelia (1752): “If the lady says another such words to me ... I will darken her daylights” (that is, put out her eyes). Hell here is simply a swear word used for emphasis. The more vulgar shit and the politer stuffing allude simply to knocking out someone's insides. Tar is more puzzling but has been so used since the late 1800s.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.