In Big Love he owns 3 adjacent houses, with a huge shared back yard, and spends the night in each (including the wife that lives in it) on a roster system. The wives are called "sister" wives so there's no threesomes or foursomes happening
The reality of that situation would be that since each wife only gets you every third day they're going to be 3 times as horny. You're expected to perform every single night and go above and beyond because she hasn't had it for 3 days.
It's a weird lifestyle but it's a great show... apart from Bill Paxton's wooden acting...