To take a whole pouch, portion, or section of a packaged snack food or muchie. This can included, but is not limited t: A tube of Oreos, a tube of Ritz crackers, a packet of Pop Tarts, etc. Also as small as one bag of chips in a 6-pack of chips, or one fruit-roll up of the whole 12-pack.
These are normally shared by between two to several people, but a single "sleeve" can be eaten by one person (And certainly should!)
Y: Thanks doood. I need dem' muchies.
H: Sleeve that box and take it into the car, we have to go!
K: Wait a second, I still haven't sleeved the cookies yet.