Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
free gift
is redundant and tautological, an unsolicited gift of the advertising trade. Perhaps the hyperbole has been called for because in our commercial world (where there is certainly no free lunch), seldom is anything truly without cost to the receiver. To use free gift other than jocularly is unwise: Standard users scorn its serious use. See TAUTOLOGY.
