Now you reminded me my friend in high school had one of these in the backyard. It was a wood shed but pretty roomy, had full carpet, a mattress laying on the ground but fully sheeted, and most of all had a TV and a window AC unit made from a custom window cut into the side. It was basically our hangout room as we could make as much noise as we wanted and not bother his parents which I assume was the point since my friend also had his drum set in there.