I had a secret crush on a girl who just started seriously with someone else and she suddenly appeared and wanted to talk like we used to do. I couldn't talk. I just froze as in 'all choked up that you're ok'. I must have blushed also and she could see I was 'falling to pieces'. Definitely my most embarrasing moment since now my secret was known. I avoided her until I could leave the area and I never saw her again. That was over 15 years ago but it still hurts like yesterday.