I am a "fan" of certain debunked scientific or psuedoscientific theories, by that I mean I don't believe they are true but I enjoy thinking about them.
Three are:
- the deep, hot biosphere
- humans are aquatic apes
- caffeine birthed the enlightenment
All fun! Some have complex, interesting and layered histories, for instance humans are aquatic apes was more credible than initially recognized; it was dismissed not on scientific grounds but out of sexism-- or at least this is one side of it