From Etymological Dictionary of the English Language, WW Skeat:

JERK to give a sudden movement, throw with a quick action. (E.) Cotgrave has: "Fouetter, to scourge, lash, yerke, or jerke." In Shak. as a sb., L.L.L. iv. 2. 129. "A ierk, verber;" Levins, ed. 1570. "With that which jerks [lashes] the hams of every jade;" Bp. Hall, Satires, b. iii. sat. 5, l. 26. Lowland Sc. yerk, to beat, strike smartly; a smart blow. "To jerke or gerke;" Minsheu, ed. 1627. "A girke or yerke of a rod or whip;" Minsheu's Span. Diet. (E. index). Halliwell also gives: "Girk, a rod; also, to beat." Another form is jert. Cotgrave has: "Attainte, a reach, hit, blow, stroke, ... a gentle nip, quip, or jert, a sleight gird, or taxation." Moreover, the words jert and gird were regarded as equivalent; thus Sherwood has, in his index to Cotgrave: "A jert or gerd, Attainte." The words jerk, jert, and gird are probably all connected, and all had once the same meaning, viz. to strike, esp. with a whip or rod. The only one of these three forms found in ME. is gurden, girden, to strike; see gurden in Stratmann. ... It may be added that the usual meaning of jerk in old authors is to whip, to lash; as partly shown above.


From Slang and Euphemism Dictionary, Richard Spears:

jerk 1. to masturbate. [British, 1800s] 2. a masturbator. From JERK OFF (sense 2). For synonyms see HUSKER [US Slang, 1800s-pres]. 3. an oaf or incompetent fool. The connection with sense 1 is rarely recognized [except on the AWAD board]. [US slang, 1800s-pres] ...

I shall now snigger whenever I speak of the Nebraska Cornhuskers, for reasons other than their basketball prowess.