MILF and Cookies?

Just curious -- When did MILF slip into mainstream lingo? The WB website now streams online videos of many of its t.v. shows, both old and new. The advertisement on this site for The Gilmore Girls is "MILF and Cookies." I was a bit taken aback by such causal usage this term for a show that's pretty wholesome. (By the way ... is there a male counterpart to MILF or do we just assume that all men are fuckable regardless of progeny or age???)