Someone who acts like shit, a dung dweller. An unexpected insult. (WARNING: probably don't use this in a real situation unless you use this with some other insult)
Norman: LOL, you're so bad at this game, I could easily mutt you.
Eddie: Dude, you have more deaths than kills, you dungling.
The phrase said by a self proclaimed "pro" but in reality its a skinny ass bitch that's probably in 4th grade and has no friends. You will see this phrase used again you if a toxic kid in a video game thinks you're complaining or something, namely roblox or cod.
you: "dude, just stop being annoying, I can report you"
kid: "stay mad ez"
you: "what a headass"
To be so mad you bald, like instead of telling someone to "stay mad" just say "Mald"
John: DUDE! WHAT THE HELL! YOU'RE HACKING!
Mark: Mald