Bhut Jolokia's are the way to go if you're manly.
But you really should put the baby wipes in the fridge in anticipation of some pain.
I use chilli oil too, which I normally make fr Add from the previous years batch of chillies. Garlic, ginger, Onions and chillies, then add the beef, browned, then add cumin and oregano (dried) and stir in.
Add toms and Kidney beans, then flavour with soy sauce (dark), balsamic vinegar and if you're feeling mighty, add a chipottle chilli in, as it adds a glorious smokiness to it all. At the end, stir in a tablespoon of dark muscavado sugar and a load of fresh oregano.
Yummy, if a bit wild on the 'will defintely clear your pipes out' front.