A child with ADHD was in a school play. He was supposed to say his lines at a certain point. But when the time came, he was so distracted by the shiny costume of the character next to him that he completely forgot his lines and started talking about how cool the costume was instead. The audience found it really funny.
Once, a boy with ADHD was on a school trip. They were at a museum. Instead of following the tour guide, he got distracted by a display of old toys. He started playing with them right there, pretending he was in his own little world. His classmates couldn't stop laughing at his antics and the tour guide had to gently pull him away to continue the tour.