"The female equivilent (sic) of Tea Bagging
" (according to Wikipedia's entry for "Teabagging" as of 19 March 2009); ergo, the act of pressing ("stamping") the vagina against the mouth or on or around the face (including the top of the head) of another person, often in a repeated in-and-out motion as in irrumatio. This practice can leave a pattern of viscous moisture on the recipient's face or head, vaguely reminiscent of a slight trail of slime a slug would leave were it to travel around someone's face/head.
Although this term is acknowledged in Wikipedia, it does not seem to be prevalent on the internet at this time.
Mary spent quality foreplay time slug stamping Pat before fully grinding her 'gina on her lover's mouth.