Verb: a prank/vengeful sexual act where a man ejaculates onto his partner's pillow while they are sleeping in hopes they will roll into it, only to wake with the pillow stuck to their face, resembling a marshmallow.
I can't believe that bitch did that shit. She's getting a sticky marshmallow tonight!
When you take an iron or some other hot object and burn your girls pussy till it is charred black. Proceed to insert your penis and jizz and there you go. The sticky marshmallow
She said the sex wasn't hot enough so I made it hotter with a sticky marshmallow.