jerk off (v.) Look up jerk off at Dictionary.com
slang, "perform male masturbation," by 1896, from jerk (v.) denoting rapid pulling motion + off. Farmer & Henley also list as synonyms jerk (one's) jelly and jerk (one's) juice. The noun jerk off or jerkoff as an emphatic form of jerk (n.) is attested by 1968. As an adjective from 1957.