In 10th grade (or 11th, I forgot), I was in line waiting for the teacher to get the key to the changing rooms in my physical education class. I was having a shit day and I was listening to an album I downloaded the night before. The guy in front of me tried to strike up a conversation with me. I was reluctant, but I responded halfheartedly to his questions about the music and about me. He was remarkably friendly. I don't even know if he was in my class or the adjacent one that shares the facilities because I attended so infrequently. I only vaguely remember his face and voice. It was a brief exchange and I really regret being so terse with him. I switched classes the next day for one reason or another and never saw him again.
When I was a kid, I had a female friend. I really liked her, but whenever we were together, I'd be quite horrible to her, insulting her etc. I couldn't think of any other way to joke around with her and I'm amazed she even talked to me for as long as she did. After a summer holiday, realising how horrible I acted around her, I avoided her, not even wanting to try being friends again out of fear that I'd go back to my horrible ways and make her life worse. ;_;