Some people like their chilli peppers hot whereas others simply do not. Apparently it all depends on an individual’s palate and how many heat receptors they have in their mouths, and we’re all different.
Chillies contain a chemical compound called capsaicin which is an irritant and causes that well-known burning sensation. Capsaicin is used as pepper spray for personal defence and also on occasions for riot control, so it really is pretty powerful stuff.
Back in 1912 an American pharmacist, Wilbur Scoville, developed a way of measuring the level of capsaicin in different varieties of chilli pepper, the Scoville Scale. The number of Scoville heat units (SHU) is related to the level of capsaicin in that particular chili. Other more sophisticated measure have been introduced since but the Scoville Scale remains the most widely used indicator as to the heat of those red hot chilli peppers.
Currently the Bhut Jolokia is considered the hottest chilli with an SHU of 1,000,000. Californian Jason McNabb ate 13 in 2 minutes and earned himself a place in the Guinness Book of Records. Now why would you?