The hottest (natural) pepper is actually the Trinidad Scorpion Chili. It has on average more than 1.2 million SHU (with some up to 2 million SHU). 2nd place is the Indian Ghost Chili (or Bhut Jolokia) with an average of 1 million SHU.

To put that kind of acidity to perspective, the habanero chili pepper is 100,000 to 350,000 SHU, the jalepeno is 2,500 to 8,000 SHU, and the Peruvian death pepper is 100,000 to 200,000 SHU.

So the Trinidad Scorpion Chili is about 6 times the SHU of the habanero and the Peruvian death pepper.

Basically, you wouldn't want to eat one.