A sleeve tattoo covers most or all of a person's arm. Do you know anyone with a sleeve?
I use to know someone with a sleeve tattoo. It was entirely Pearl Jam-themed. But I haven't talked to him in years. 
Apparently they also use this term to refer to a large leg tattoo - but I've never personally heard it called that.
A leg sleeve? I've never heard of that either. I've got a few tattoos myself. Someday I'd like a half sleeve, but probably not the whole thing. On my arm, of course, not my leg. 
Yep a leg sleeve LOL!  You could get a quarter sleeve that only covers part of the arm 
That's probably what I'd want. Do you have any tattoos?
Tattoo
A tattoo is a form of body modification where a design is made by inserting ink, dyes and pigments, either indelible or temporary, into the dermis layer of the skin to change the pigment. The art of making tattoos is tattooing. 
Tattoos fall into three broad categories: purely decorative (with no specific meaning); symbolic (with a specific meaning pertinent to the wearer); pictorial (a depiction of a specific person or item). In addition, tattoos can be used for identification such as
Sleeve tattoo
A sleeve tattoo (or tattoo sleeve) is a large tattoo, or a collection of smaller tattoos, that has a unified theme, that covers most or all of a person's arm, usually from shoulder to wrist.
There is a difference between an arm covered in tattoos and a sleeve tattoo. A sleeve tattoo has a unified theme, whereas an arm covered in tattoos may have many tattoos of different styles that does not have an overall unity.
The term "sleeve" is a reference