Used as a replacement for any verb, marf can be useful in many situations.
Forms- Marf, Marfing, Marfed
Me and Dave were marfing last night, and he marfed my fucking keyboard! I am going to marf him into 1985 for that shiz!
To shove one's fist up another's ass. Also known as "fisting".
"I was neffing the wife last night, and she shat on my arm!"