The act of expressing intent to finish what one has not already finished; it is particularly (but not solely) used to voice one's wish to finish the smoking of another's cigarette.
"Bro, let me get shorts on that sandwich."
"Shit i forgot my pack, can I get shorts on your square?"
(Hector) yo Lopez, save me shorts off that square.
(Lopez) fuck off G, go get a paper route and buy your own biotch its my last one.
or-
dude, i just lost my mcjob, can you save me shorts