I bought a mattress a few years ago. I bought one of the more expensive ones, partly because I should be careful with my back. The salesman told me how great that mattress was.
Then he started about one of those things you put under your mattress, the pieces of wood. He had a very luxurious one. I asked him if I needed such an expensive one, because I already have such a good mattress. He admitted I didn't need it.
Hehe, back then I was afraid I invested in a 1 person mattress while I would be needing a 2 persons mattress pretty soon.
