A often secret pocket to stash different things of often high value.
"Hey Mike, I can't carry this shit with me, but I can't just leave it either.." "Well dude stash that shit up in one of them stashpockets! I got one just around the corner!"
The permanant hole in a junkies arm used to stash their drugs
Not Junkie: Man, i think theres something wrong with your arm.
Junkie: Aww naww man, that's just my stashpocket actin' up.