Which lead me to contemplate IKEA: The LARP. Just think about it: there are enough 'locations', you can pretend to live in one of the 25 square meter houses that are everywhere, and NPC's are in ample supply (the bit about their glazed looks is spot on!).
I predict the LARP would last for all of five minutes though, 'cause you'd get thrown out because you were freaking out the NPC's or (god forbid!) their children. And I don't think the management of the local Ikea would want to accomodate an official LARP...
Here's another game for you to try at Ikea: make photographs of the merchandise. It took the employees less than three minutes to sniff out a camera and order us to stop taking pictures.
I always get a rather uncomfortable in the Ikea. It always feels like an elaborately fabricated lie. A lie where everybody is always happy and content in their colorful surroundings, where kids are always well-behaved and play with their wooden toys, where every accesory is carefully picked to match and complement the rest of the living environment, to maximize the well-being of the residents. It just feels... fake. Instant happiness out of a catalogue: Ikea markets the feeling, not the products.
This being said, I must note that we have a lot of Ikea furniture. The price/quality ratio is pretty decent, and luckily we have some stuff of our own to mix in.
I also think my Viking-icon is rather appropriate here. ;)