I don't remember exactly what level this was on, but I do remember it was in SMA2, Super Mario World, and in Vanilla Dome
I was in an underground area, near two charging chuck's guarding both sides of a medium slope. I jumped on one, and aimed for the center of the slope, fell through, and died.
The reason I don't remember the level- This happened over a year ago. But it still haunts me at night.
Too many numbers...