A jack shack is a place like a seedy massage parlor or "modeling studio" or "gentlemen's spa" where you can get a hand job for a reasonable price, and little fear of getting arrested for soliciting.

A term used to reference cannabis/marijuana/weed.

Usually specific to soldiers, or other people who are forced to live in close proximity for long periods of time without either sexual activity or privacy, a jack shack is a small shack made out of blankets, ponchos or poncho liners that is erected so that the builder can masturbate in relative peace. It is often explained away as a means to block light, or provide privacy to change, despite being erected almost exclusively around one's sleeping quarters.
syn: whackatorium

An establishment that provides cost effective massage treatments of the sexual variety. Also known as a massage parlor.

A shed, shack, camping shelter, tent or other shelter which provides protection from view and privacy, when used by the inhabitant (often a teenager) to masturbate, smoke marijuana, or drink alcohol without being discovered or disturbed.

When a inmate put his sheets around the bottom bunk to make a shack to Jack off in

A building which sells sex toys and porn videos and has 25 cent peep shows in the back room.