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 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.
My family doesn't give me any privacy so I have to go to my Jack shack in the woods when I want to rub one out or smoke a joint.
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
He had only been in Iraq for a week, but he had already built an intricate and comfortable jackshack.
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the USCoast Guard in the area of Southern Florida.
"Base we've got some square groupers floating outside of Miami harbor."
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.
I had a trucker's tan after driving for 10 straight hours on a sunny day.