This probably applies most to those people whose self-discovery of WAM predates the internet.
When I discovered I liked getting messy, I thought I was alone in the world, and with no point of reference, I created my own terms.
I used to call WAM sessions "wet wanks", on the basis that I used mostly shaving foam at the time and shaving with foam is called a wet shave.
I also used to test the consistency of messy substances by squeezing them in my hand and seeing how much it sucked/resisted when I pulled my fingers away from my palm. I used to call this how much it "breathed".
Anyone else come up with their own terms before encountering the general lingo?