Green’s Dictionary of Slang

bliff n.

the vagina.

1997		Roger’s Profanisaurus in Viz 87 Dec. n.p.: bliff n. Minge; front bottom.
2005		Roger’s Profanisaurus Rex.

In compounds

bliff mag (n.) [mag n.⁴ (1)]

a pornographic magazine.

1997		Roger’s Profanisaurus in Viz 87 Dec. n.p.: bliff mag n. Pornographic magazine; jazz mag (qv); art pamphlet.
2005		Roger’s Profanisaurus Rex.