1. Africa. Huge mosquitoes, hundreds of types of animals that can kill you, civil wars in several countries, widespread AIDS.
2. Latin America including Mexico. Political unrest, drug traders with machine gun-toting enforcers, unstable governments that change at a moment's notice.
3. Eastern Europe and Russia. Wealthy sadists who lure you into torture porn traps, cold weather, backward communist block accommodations.
4. Non-Japan Asia. Brokedown Palace-style drug smugglers who get you undeservedly thrown in the grossest prisons ever, the fact that noodles are a part of nearly every meal (I'm not a noodle guy), terrifyingly controlling governments that will get you caned for spitting on the street.
5. Antarctica. So cold even the penguins sometimes die, mean polar bears.
So yeah, I'd pretty much only visit western Europe, Japan, Australia and Canada.