You might assume that a sex doll is a rubbery, blow-up thing that's a bit, well, icky. But while sex dolls have always led a bit of an undercover life, these life-sized lady-like love toys have a surprisingly practical history. They were first developed for sailors who were isolated on long voyages. Later, they distributed to German and Japanese troops to help reduce the spread of disease.

In more recent years, we've seen the creation of ever more life-like sex robots, which you can have delivered right to your door. OK, so those are pretty creepy. But maybe it's best not to pass judgment; many of us grew up with Barbie, whose design may have been based on a German sex doll that was tested for troops in Nazi Germany.