The excavation commenced one afternoon. I applied myself vigorously at first. It soon became clear that the people who dig real tunnels probably aren't using a six-inch square spade designed primarily for sandbox use. I think the hole ended up being about a foot deep before I tired of this game. But not before I struck what I thought was a rich coal seam. More likely it was the leavings from someone's hibachi, but I entertained brief fantasies of retiring early from Elementary school and living out my life as a coal baron.
My dad eventually dug deeper and planted an azalea in the hole. That was the end of my tunnel-digging phase.
Another time, I was playing mountain climber on our back hill using a massive claw hammer that looked like a climber's pick. I swung a little too vigorously and embedded the claw in my ankle. 20+ years later, I still have a tear-drop shaped scar to remind me of that one.