There's a perfectly good explanation

My six year old takes a gymnastics class at the local high school every Monday evening.

Because this class starts before Adam gets home from work, I have no choice but to take her two year old sister along to watch.

Because she's a two year old, she has no interest in watching; she wants to join in and climb on the balance beams and bounce on the trampoline and run around with the cool flowy rainbow ribbon things.

Because I don't want to spend an hour and a half wrestling with her while she screams in the bleachers, I opt to take her out into the hallways of the school and let her run up and down, playing with combination locks and trying to outrun the reflections of the lights on the tiles.

Because several lockers are empty and unlocked she likes to hide in them, then jump out and yell BOO!

Because she told me to, I ran away from the locker and hid in a little alcove after she shut the door.

Because I thought it would be funny, I jumped out of my hiding spot and grabbed her when she eventually came out and ran down the hall looking for me.

Because she laughed, we did it again.

Because I had to move fast to hide before she opened the door, I stopped paying careful attention.

Because I heard little feet running, I leaped out with a yell to grab my daughter.

Because the child in front of me was not my child, he started to cry.

Because his mom was clearly wondering what the fuck was wrong with me, I apologized and explained that I had mistaken her son for my daughter.

Because my daughter was nowhere to be seen, his mother looked at me like I was on crack.

Because she has awesome timing, my two year old started banging on the inside of her locker, begging to be let out.

Because I'm a psychopath who likes to scare the bejezus out of toddlers and then trap them in school lockers.