Originating durring the times of shanty or shack towns, the local shack wacker was a man or woman who constantly masturbated while inside their dwelling.
When your bed is completely enclosed/surrounded by a bed sheet providing ample opportunity for "private time."
Options for building your wack shack:
1. If you have a bunk bed, the easiest way to create a wack shack is by sleeping on the bottombunk and draping the sheet over by putting one half under the top bed's mattress allowing for the other half of the sheet to hang down to the floor.
2. If you are not so lucky as to have a bunk bed, tacks and the ceiling are your best bet.
Benefits:
1. Noise reduction
2. Light reduction
3. Alone time
4. Girlfriend time
Joe just went into his wack shack...you know what the f*** is up.