Eccentric / ridiculous / ingenious ideas

I once saw a build (maybe on here?) where the person had built it up with two gears. 2 chain rings on the front, two cogs on the back. To change gear, the rider had to stop, take the chain off, and put it on the other set of chainring/cog. Which is obviously mad. And incredibly impractical. But fun

This echoes the Moulton Marathon. Here is a quote from Colin Martin who originally owned it in 1970:

"The transmission was unusual - a Fichtel and Sachs 2 speed automatic rear hub with a combined backpedal brake which, with a double chain ring and two sprockets provided a choice of two sets of gears (48"-67.5" or 34"-48"). By appropriate choice of chain wheel and sprockets sizes a high gear and a low gear is obtained by slipping the wheel forward and moving the chain manually."
Source: https://www.flickr.com/photos/stevenbrandist/11614089586