New inventions are tricky. The right idea can earn you millions and change peoples' day-to-day lives. The wrong idea will either be left in the dust or worse - become the butt of the joke for years to come. For every post-it note or paperclip, there's an egg-cuber or sauna pants. Below we celebrate retro products that never quite caught on. Whether because they were impractical, ridiculous, or downright dangerous, we can be glad these items didn't really stick around.