My story sounds like Ron's.
As a kid, I didn't have a hobby knife, never heard of an Exacto or whatever.
Was using a razor blade to trim something on a model, slipped, sliced open my thigh (summertime, was wearing shorts, sitting on the floor). Successfully hid the injury from my parents. Should have had stitches. Still have a big scar.
And just to think that my parents thought model building was a nice, safe, indoor activity to keep me out of trouble....