A fluffernutter is an overly zealous or eager person.
On a pornographic set, the fluffer is charged with the responsibility of keeping an actor's penis erect without causing him to ejaculate. The fluffernutter fails at their sole job requirement when their enthusiasm triggers a "nut".
1. Your pillows are really hot if like to fluffernutter in them
2. "dude when I pulled down my pants this morning, I realised I had fluffernutter in them"
(n) A hand-job where peanut butter is used as a lubricant. When the male ejaculates, the semen (aka "marshmallow fluff") is then mixed with the peanut butter, reminiscent of a fluffernutter sandwich.
I didn't know what she had in mind when she brought out the peanut butter, but then she showed me the "fluffernutter."