In marijuana culture, snappers are also sometimes refered to as "One'ies" (Wun-Eez). Basically you pack just enough to get one good green hit and then have it extinguish on its own. Efficiency is the name of the game with snappers.
"dude, my jar is almost empty so we should just do snappers"
The act of inserting ones member into a jelly jar with the intention of using it to jerk off.
Junior should've taken his underwear out of the squad car when he was done with his jelly tugs.