Pop cans are pretty handy for those in the military who live in the barracks. Although, we had an inspection once and when they moved my duffel bag, a used pop can that I'd forgotten about fell off my locker. My roomie saw that I'd smoked with it, and calmly picked it up and threw it in the trash, so I didn't get busted.

Sometimes ya just gotta make do with what's available, and nobody keeps pipes or bongs or papers when they're living on base; that's just asking to go break rocks for a few years.