Parallel Acts Of Idiocy

What was something you did as a child that was incomprehensible, embarrassing and well...normal for a little one. I read about the naughty act of one 12 year old in Detroit, Michigan the other day, and it reminded me one of my own most memorable childhood stupidities (I had quite a few).
I tell you about the Detroit child's deed later, first I am ready to confess (do I get amnesty?) my own. It occurred I was in first or second grade and it happened, like the Michigan kid's, at a museum. Our teacher had taken the class to an art museum in New Orleans as part of a day long field trip. Being a bit playful in those days I was up to amusing the others in the class ( Hey! They expected the entertainment from me. I was better at entertaining than studying). As we entered the museum that day the class was given the perfunctory "do not touch or get too close to the paintings and object speech".
Uh..as always, I wasn't; paying close attention. I already saw the object of my play while she rambled on about being responsible. It was, it turned out a rare and expensive, damaged painting that had been mounted in a rolling device. As soon as the safe watching lecture was over, I called over a couple of fellow idiots from my class. "Hey, watch this"! I said. I then proceeded to walk behind the roller and inserted my entire arm through the back of the painting, where it had been damaged, Almost immediately I hear a shriek from the "safety lady".
I thinks she said something to the effect, "You little brat!", but whatever it was I deserved her critical remarks. Fortunately, my stunt did to enlarge the tear or cause any further damage to the painting. My classmates laughed and cheered my idiocy (sigh.,. as always). In my defense, I must say I was the top student (even though I never studied), and that my teacher should have expected such shenanigans from em and kept closer watch on my miserable soul. The safety lady screamed "Out. Out..the entire class out!" and security escorted my class out onto the New Orleans streets. I, uh, got us kicked out of the museum.
Fewer than five minutes in the museum and we were booted and banned. The rest is something of a blur but I do know they did not execute me when we returned to school. The teacher was nt fired and she didn't hold a grudge against naughty little Jimmy (that was me). Hehe I do remember that we didn't take any more field trips that year. Hehe You might say that I rewrote the curriculum for the class that year.
Now for my twin's story. In this case the unnamed 12 year old visitor to the Detroit Institute of Arts was also part of a school field trip to the museum before the end of the school year. This time the damage was more than symbolic. You see, the boy admired Helen Frankenthaler's abstract painting "The Bay' so much that he decide to add to it. After a quick glance he took out of his mouth his piece of chewed Wrigley's Extra Polar Ice gum and stuck it on the 1.5 million dollar painting, leaving a stain the size of a large coin.
Hmmmmmmmm It's a good thing I didn't sneak a piece of gum before going into that museum I was kicked out of. The child's gum left a chemical residue that officials hope can be cleaned with a solvent. According to the school, the boy has been suspended for several days. Ok...you must have your own childhood school horror story to tell. What is it?