Sleeper OP 

A character in a video game that is simply too strong (overpowered, or OP for short), but not many poeple realize it (yet), hence the "sleeper" part.

This is likely due to the fact that when a new version of a game comes out, it takes a while for people (including some pros) to adjust to the new meta game and rather stick to the same staple set of popular overpowered characters (sometimes despite nerfs) out of comfort instead of trying to discover new ones.

This is NOT related to special snow flakes that somehow made a bad character work against all odds in 1 out of 100 games; Sleeper OP is legit broken, it's just known by the unenlightened masses.

When the Sleeper OP char becomes common knowledge, it loses that status.

Term originated in League of Legends.

Player A: LUL why you pick the Merchant, he's trash.
Player B: Nah man this is 0.24 Merchant, meta sheep just haven't caught on. Merchant Sleeper OP
*PLayer A gets obliterated by Merchant*
Player A: You just got lucky, Merchant sux!

Sleeper OP by Han shot in between November 1, 2018

Sleeper OP 

In multiplayer games, a character who is indeed OP but it is not yet recognized by the playerbase as such. Usually one or two buffs away from being broken.

Player 1: I rarely ever see Swain in games but when he's there he always stomps
Player 2: He's definitely sleeper OP

Sleeper OP by Quacking August 22, 2017

Sleeper OP 

Usually in reference a playable video game character . The words "Sleeper OP" means that the character is easy to play and over-powered at the same. So over-powered and easy that you could be asleep and still play them well.

Jim;"Jinx is sleeper OP.. Riot need to gut the fuck out of her"
Kathy;"I agree, fuck that bitch."

Sleeper OP by TheDefinist. January 23, 2015

sweeper operator 

One who cleans up your mess- sweeper operator.

“Joe get that dirt off the road, don’t worry about it mike the sweeper operator will pick it up!”

sweeper operator by Operator891! August 22, 2019

sleeperoni 

A funny way to say "sleep".

stop sleeperoni and gtfo

sleeperoni by waddupppppp December 11, 2017