means A jerk is a quick, sharp, sudden movement or pull — and, used of a person, someone who is contemptibly rude, selfish, or obnoxious.

from The motion-word 'jerk' appeared in the 16th century, probably as an imitative coinage — a snap of a syllable mimicking the snap of a sudden tug, much like its onetime variant 'yerk.' From the abrupt physical motion came a string of figurative uses, and the insult is American slang that bloomed in the early 20th century, often traced to 'jerkwater town' — a tiny rail stop so minor that crews had to jerk up water by hand — giving 'jerk' the flavor of a worthless backwater nobody. The jerk you eat is unrelated: that 'jerk' (as in jerky) comes from the Spanish 'charqui,' itself borrowed from Quechua 'ch'arki,' meaning dried meat — a coincidence of sound, not of family.