I may have to try this... but if I do it wrong, am I going to die? Eating a scotch bonnet doesn't sound like a good plan to me!
Seriously, though, the fat in the butter will line your mouth and tongue very nicely, dissolving the oleoresin capsicum or most of it on contact, and you will not (unlike the mark) suffer at all.
I write the inventory software for Heimos Produce (freshest peppers in STL, I guarantee it) here in STL, and I got two of the guys with this little trick (without the side bet -- didn't want to louse up a good client relationship after all!).
Then, they insisted I try it out on the boss, Jim Heimos. Turns out Jim hates hot peppers, he wouldn't play, but the general manager loves them...so he got his turn. Pretty tough tongue he has, too. Took about 60 seconds before he yelled 'uncle' and zipped off to the kitchen. I just looked at Jim and blandly said, ''Really good peppers today.'' The two salesmen told him what was going on, and he just cracked up.
Who says ya can't have some fun at work, eh?
;^)