A tongue in cheek (no pun intended) way of describing cunniligus or the stimulation of a woman's vagina with a man (or woman's) mouth, tongue, teeth, lips, etc.

If you need to ask this question, then you need to study the list of acronyms on the Newbie Board big time; or else a lot of the info on here is going to go over your head.  (Still no pun intended.)

In fact, you should make it a point to read the entire Newbie Manual to really figure this whole world out.