About 3 or possibly 4 years old. Had just finished watching the circus on the telly at a friends house and remember being enthralled by the knife-throwing act. My then friend, unable to find enough kitchen knives (WHAT!!) managed to purloin his dad's set of darts.
Fortunately, even at such a tender age, I refused to stand against the fence with an apple on my head, but instead proffered my outstretched, open hand. You could hear my screams from 20 miles away as the first dart struck the palm of my hand, dead centre, pinning it to the wooden fence.
My Mom tanned my hide for a week for being so stupid.