I was at a fast food restaurant in Hong Kong which was apparently popular for its spicy dishes - there were cartoons on the walls and lots of red peppers everywhere. It looked like a chain, sort of on the level of In-N-Out or Five Guys, but with spicy ramen. My wife and I ordered different dishes and they both were, well, spicy.
But! This spicy-ness was a different sensation than I've had before or since, and I can't find what was causing it! The best way I can explain it is lots of little ants with hot feet running around on my palate. This isn't very appetizing, I realize, but it was delicious - usually, hot foods will spread out evenly around one's palate, but this was (I'll try again) like those "pinhead" toys where each bit of hotness was a separate point (rain on a tin roof?) It was delicious!
I hope I've given enough clues for someone to tell us what the heck this was!