I made a Neverending Party Bunker once in TS3 that featured:
* Completely fenced with the only entrance set to only unlock by a household member. I think I also had to make a kind of airlock setup to get around some of the AI pathfinding behavior.
* Large bandstand (The household all played musical instruments, and had a rotating schedule, so there was pretty much always music going on). Benches and other furniture for the "guests"
* Stairs leading to an underground bunker with barrack-style bunkbeds, basic food/bathroom facilities, some recreational odds and ends, and the most eye-peeling psychedelic wallpaper and flooring I could devise.
The way it worked is that one of the household would invite a bunch of people to a party, let them through the gate and then never let them leave. They would hang around for awhile, try to leave, and get mad that they were stuck/hungry/tired, but then get distracted doing something, cycling through this pattern until they collapsed from exhaustion. Sometimes they would use the beds, but mostly they slept on the benches (where they got horrible sleeping moods from sleeping outside with loud music going all night.
Eventually, the pathfinding would get completely borked once I got enough people on the lot (15-20) and sims would start teleporting on and off (mostly off) the lot.