I first saw someone do this experiment at a science show at the Boston museum of science, back in the 80s when I was little. It's always been one of my favourites. Simple, effective and dangerous. This experiment should only every be tried by experts or under the supervision of experts who have experience with flammable gasses. I've done that experiment literally hundreds of times, and I still give it the respect it deserves. Play with fire, you'll get burned.
The secret lies in the fairy liquid. Enough foamy cool fairy liquid creates a viscous layer of fire resistant material on your hands. Using a flammable gas such as propane or methane to create bubbles filled with burn able gas, you can- with enough foam on your hands - pick up a handful and have someone set it alight. That was how Lydia and I did the " hands on fire " experiment.
Thanks for your question. Stay inspired.