Fish Poison

http://pn.bmj.com/cgi/content/abstract/7/5/316

It's weird. A poison called "ciguatoxin" from tropical fish can have a "reverse temperature" effect, meaning that cold things feel very hot and hot things will feel like icy. Also, it could cause you to have imaginary feelings about loosing teeth. There's been a few cases reported on this kind of rare poison.

The poison is produced by micro-organisms in tropical regions, and when fish eats them, the poison builds up for life. Also, the poison very often still remains on the fish long after it's been eaten.