Is it ensure, insure, or assure?
by 1936 as an expletive, from present participle of frig.
"to move about restlessly," mid-15c., perhaps a variant of frisk (q.v.). As a euphemism for "to fuck" it dates from 1680s, earlier as "to masturbate" (1670s). Related: Frigged; frigging.
Wretched; accursed; damn, fucking: if we could find the frigging truck/ You're a walkin', friggin' combat zone
: They friggin' loved it (1930+)
take a flying fuck
[ultimately fr Latin fricare, ''rub'']