Lighting a charcoal grill with liquid oxygen: https://www.youtube.com/watch?v=UjPxDOEdsX8
It reminds me of a comment I once read about how alien visitors, upon arriving on Earth, would be appalled to see how we live our lives at the bottom of a giant gaseous ocean of 20% oxygen.
Almost everyone and everything around us of any importance is one mishap away from going disappearing in a hot, sooty flame.
I was holding the camera for some of these videos. Such a great time!