mumphead 

someone who publicly buts in, or intrudes into a private argument or disagreement between two people and denigrates both parties.

This behavior is often seen in a Restaurantor Pub. The Mumphead does not have to know the people arguing. He is more concerned with intruding into the conversation.

mumphead by Imactive March 6, 2005

Mumphead 

A crafty insult to use on fattys, kids, and geezers.

“Haha! You suck! Mumphead!”

Mumphead by papermoonkinglol May 28, 2021

Mumphed 

To "Mumph" is to lay out over a chair or couch/sofa in a state where you do not care what you look like, but just want to relax.

Christopher mumphed on the chair with a slice of pizza in one hand and a diet coke in the other, oblivious to the people staring at him.

Mumphed by TYPE August 22, 2014