Sleeper boobs 

large breasts that are cleverly hidden, most of the time

Damn Eric, Jane is totally rocking the sleeper boobs under that big bulky sweater...she thinks she's hiding them

Sleeper boobs by Dirt Rider June 2, 2009

sleeper leaper 

Trucker slang, refers to a beaver or buffalo who is known to go from one semi to another, servicing the drivers. From the practice of moving between two closely-parked semis via the opened side doors of the sleepers, without touching the ground.

That truckstop is real popular, there's plenty of sleeper leapers to go around.

sleeper leaper by Mount May 22, 2004

Sleeper car 

A boring looking car that could beat a high performance car in quarter mile drag race

Lamborghini car owner: let’s see if your hunk of junk can beat my lambo

Sleeper car owner: yeah sure

*they race*

Sleeper owner: YOU JUST GOT BEATEN BY A SLEEPER CAR!

*race ends*

Sleeper car by Newah August 9, 2021

Sleeper Dox

Sleeper Dox is what you call a good rapper/trapstar when there on stage rapping, doing there thing!

person:1 Man that guy is an awesome rapper

person:2 I agree, I think hes a Sleeper Dox too!

Sleeper Dox by alexander-keith March 14, 2010

Sleeper Movie 

After watching a movie your first impression of it was that it was mediocre at best, yet after a few hours or days have gone by, the movie keeps popping in and out of you thoughts. So, at the time of watching the movie you had no idea it would have such a profound effect on you and yet now its all you can think about. It crept up on you so to speak.

Mike: Dude, I just saw Adventureland last night, and I didn't think much of it at the time, but now its realistic portrayal of teenage life suddenly seems so much more relevant.

Joey: Dude, you just saw a Sleeper Movie!!

Sleeper Movie by AShotKid June 2, 2009

Sleeper cell 

A sleeper cell is a person who surprises you with some trait of attribute that was formerly unknown.

"Jake took off his shirt to reveal that he had a six pack... And that's when I knew he was a sleeper cell"

"Jenny seemed like an idiot ans then I found out she's Rhodes Scholar, that chick's a sleeper cell"

Sleeper cell by Cakelillo July 10, 2015

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