In pre-kindergarten/kindergarten a kid I used to play with, Patrick, punched me in the stomach (I have no idea why.) I was mad and I was a naive 4-year-old – I had no concept of “revenge” but was well-trained in “monkey see, monkey do.” Someone punched me and I wanted to whack someone else.
So as I stood in line to go get one of the cool toys, I was still fuming indignantly about being punched in the tummy. So I spontaneously decided to punch whoever was the closest. I looked at the boy in front of me – he was “big kid” (kindergarten) so definitely too initimidating. The girl behind me was a “little kid” (pre-kindergarten), my age and size. So I hesitantly punched her in the tummy, sort of like slow motion.
I felt really, really bad the second I hit her tummy. She burst into tears, of course. And I’ve felt horrible about it ever since. 
It had been her first day. She was the only black kid amoung the “little kids,” my friend, Mark, who was a year older than me, was the only black kid amoung the “big kids.”. It had been her first time in a “school” of any kind, away from family, friends and anything familiar. She didn’t come back the next day. She never came back. She never told on me either. 
I’ve alwasy wanted to apologize. I wanted to say sorry for being mean. And I’ve always been afraid that she thought I’d hit her because she was black, which seems doubly bad.
As a grown-up, I suspect she was a “visitor” because she arrived midway through the year in a flurry of activity. Sometimes we’d have “visitors” – kids who needed some kind of emergency daycare because their usual system for babysitting was temporarily unavailable. So once in a while, we had an extra kid in class for a day or maybe two. She probably didn’t come back the next day because she was never supposed to, but in my mind it will always because I hit her. It’s my fault she didn’t come back.
Being in a new pre-kindergarten environment is traumatic enough without having some little Spanish kid punch you in the tummy for no reason on your first day. I still feel horribly remorseful.