"to move about restlessly," mid-15c., perhaps a variant of frisk (q.v.). As a euphemism for "to fuck" it dates from 1550s (frigging); from 1670s as "to masturbate." Related: Frigged; frigging.
Entries linking to frig
frisk v.
1510s, "to dance, frolic," from Middle English adjective frisk "lively" (mid-15c.), from Old French frisque "lively, brisk," also "fresh, new; merry, animated" (13c.), which is ultimately from a Germanic source (compare Middle Dutch vrisch "fresh," Old High German frisc "lively;" see fresh (adj.1)). Sense of "pat down in a search" first recorded 1781. Related: Frisked; frisking. As a noun, "a frolic, a gambol," from 1520s.
frigging adj.
by 1936 as an expletive, from present participle of frig. Perhaps felt as euphemistic.