In the UK, it seems that pretty much anything that is somewhat car-like can be registered for use on the road as long as the owner built it in a shed. The result is mostly a bunch of crazy track-day kit cars with turn signals bolted on, but sometimes an eccentric builds something a bit more whimsical.
Take this man with three spikes emerging from his face, for example. He built an adult sized Little Tikes car that can do 70 mph, because nothing is more fun than getting hit in the face by a bee at 70 mph. He plans to use it as a promotional vehicle for children's charities, and, of course, for laughs.