If you're a child of the '70s or '80s - or your home is in serious need of some renovations - you know what it's like to sleep on a water bed.While we can't deny sinking into the water is comfy, most of us wouldn't trade our old-fashioned mattress for one of these kitschy models. But people did buy them in droves, with waterbeds accounting for 15% of the mattress market in 1986. Houston Librarian / YouTubeToday, waterbeds make up only a measly 5% of mattress sales, but the man behind the fad is looking to put them back in