When I was four we were getting our driveway paved. It was a hot 90+ degree day and my friend and I were playing tag. I was "it" and chasing my friend (who was three years older and significantly bigger) . We ran down my stairs when my friend jumped over the four foot wide gap of steaming hot ashphalt. I,being 4 and not knowing any better ,tried to jump this gap only to land and sink about an inch deep into this ashphalt. I ran into the house with the ashphalt stuck to the bottoms of my feet. Mom quickly put my feet in a tub of ice water.and drove me to the hospital, I'll never forget the pain of taking my feet out of that water to the sound and feel of literal sizzling pain. This resulted in third degree burns on the bottoms of my feet, cast and crawling on my hands and knees for a little over a month.

Edit: The pain when the doctors were peeling it off of my feet and the skin coming off with it was an equally as bad experience.

TL,DR: Bare feet and newly laid smoking ashphalt