a person who has too much sleep. dont mess cuz they r too cranky and will beat u up with a stick, machine gun, sword, machetie, or a cat. loves atackin with the cat.
"my bro is such a sleeper. he hit me in the head with a cat."
by H3R0 B01 May 11, 2006
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A mark ass bitch; someone who is a overall messy bitch but didn't show their true colors initially
Damn, dude Jess is one big sleeper for cheating on her man
by ScamuelJackson July 15, 2016
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A type of car guy with a normal, stock looking car (like an everyday person would have), but the performance of it is intense; simply the undercover of the car community.

These people will

1. Focus on all go, no show.
2. Hunts down rich douchebags in their supercars, who brags about it being "faster"
3. Modify their car's performance (Turbo, Intake, tires, etc)
4. Be the most unexpected when law enforcement gets included
The imbecile in the Ferrari 360 is to late to realize the Volvo 242 with the roaring V8 was a sleeper car
by DeadassDefs May 23, 2018
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In online role playing games, a sleeper is a character created by a player that is soon abandoned by its player. The character technically lives on in the game world but never speaks, works or interacts with other characters because its player no longer plays him/her. As a result, the character is often deemed a "sleeper" by the active characters and ignored until he/she succumbs to starvation or some other form of character death in the game or less commonly the player has a change of heart and decides to start playing the character again.
This is how it usually goes.

A character named Argon is born or spawned into the game world.

Argon: "Hello everybody what can I do to help out around here?"

Random character: " Argon, we could use a guard to help defend the city, maybe a blacksmith."
Argon: "Okay, sure."

One or two weeks later.......

Random Character: That Argon fellow hasn't spoken in two weeks. He made a hammer and then fell a sleep. He's a sleeper sojust let him starve."
by PoppaJ81 June 30, 2015
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A heavy punch delivered that knocks out the opposing side in one hit.
Taylor swift would've thrown an absolute sleeper if her and Kanye actually stepped in the ring.
by Golden Peggy May 14, 2018
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In car terms, a sleeper is any car that only has performance modifications and no visual mods. AKA "All bite and no bark"

A sleeper is the complete opposite of a ricer.
(Btw, the sleeper here is the 350Z Driver)

Ricer: "LOL, look at that 350Z. It suxxx. Mah Civic is better in EVERY WAY POSSIBLE."
Z Driver: "I see you're challenging me to a race."
Ricer: "Yo, imma show yo the real power of zis Civic. We race. And I shall win. I'm serious."
Z Driver: "Don't even try. I've got more important matters to attend to--"

-a little while later-

Ricer: "Goddamn it! YOU N00B! GET BACK HERE FOOL"
Z Driver: "No u."
(Z Driver drives away doing the "lol internet")
by N00berman October 22, 2011
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A booty that looks like it isn't much but it's actually a hidden treasure
"Bro Tracy has a a flat ass"
"Nah bro she has a sleeper trust me"
by Lil papaya October 11, 2016
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