Somebody known for screwing people over, not in a serious fashion, typically used after you (personally) have gotten screwed over. ex; such as taking a small amount of weed when your not looking, or taking the rest of the booz after you got drunk.
Guy1: hey man you got some dank stuff...can I peep?
Guy2: Sure, it's the best. I'm actually gonna run real quick to the bathroom. I've known you for years don't pull some shit like running to your car with the bag.
Guy1: ok. *waits till fully in the bathroom* *takes a decent sized nug and tucks it in sock* *whispers to self* Ayy I mean I didn't fully screw him over like everyone else, I guess this is okay.
Guy2:*comes back* Alright thanks man.

Guy1: "hey my dad wants me home, so I am going to bounce, peace out dude" *nug falls out of sock on the way out*
Guy2: "..whats this... *picks up nug* ..that fucking #screwball did it again.
Guy1: *looks at phone text* (text from guy2): "you dropped "your" nug, I'm weighing out my bag..if it is over 2 grams then you owe me, otherwise don't do it again. I'm watching you bro, next time your not allowed at my house"
Guy1: fuck! At least it wasn't a 2 gram nug. I have to take something else since my cover on my daily nug routine is gone. For now, time to screw someone else, *calls guy 3*
Guy 3: *phone buzzing* *looks at guy 4*
Guy 4: oh hell naaa, I ain't in the mood for this screwball, I finally got a new xbox controller
Guy 3: *picks up* *talks quickly*yo bro sorry i'm at work, picked up a shift till midnight. Don't call me until then or I have to shut off my phone. *hangs up* guy 4: YO we gotta bounce before this cheesecake comes and checks the driveway for our cars. Once a screwball, always a screwball.
by screwmastah P November 21, 2015

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A pony loving faggot who sucks huge and massive dick. He is an asshole and his first name usually starts with an N. His friends all hate him, and they normally refer to him as a pony faggot, as well as spam him over the internet. He likes to eat chips with his mouth open because he is a fatass. He has no brothers or sisters because he was adopted by 2 gay Russian supermodels. His vagina smells like horse because he is only fucked by ponies. In fact, that is the only type of porn he likes.
Screwball: I LIKE TO START PUNCHING BABIES IN THE FUCKING FACE WHEN PEOPLE START THROWING PONIES ALL OVER THE FUCKING PLACE, BECAUSE I LOVE PONIES. BRONY FOR LIFE.

Normal Person: Shut up you ponyfucker, nobody likes you.

Screwball: I LIKE TO EAT CHIPS VERY LOUDLY OVER TEH MICROPHONE. THEY ARE YUMMY BUT NOT AS GOOD AS PONY DICK.
by SCREWBALL IS PONY FAGGOT September 21, 2013

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a real screw up...no reference
you
by Anonymous September 25, 2003

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1) A youth with a traumatic or bad childhood/past which causes problems in the present

2) A caller of the nationally syndicated radio show "LoveLine", usually having kids at an unhealthily young age.
"Listen, all you screwballs out there, stop having children!"
by Ace Rockolla August 12, 2003

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when a fat guy screws a tennis ball
give me the goods u green clit
by doug nowlan, February 22, 2003

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