The most embarrassing moment in my life???

I had come across this question a few times before and I still do not know the answer to it. I do not know how an embarrassment should make me feel because, I am a sensitive person and I do take embarrassing moments extremely emotional. Sometimes, I become very depressed too. So yeah...

Anyway, I think I have one up my sleeve right now that I can share...

I think I was around 15 years old at the time. I was waiting for my dad to come pick me up from school. As I was waiting for my dad, I saw my brothers' old schoolmate waiting at the same spot too. They were just 5 steps away. At the time, I did not realize or even knew that those two boys had a sister who was studying at my school ( I study in an all girls school). I did want to strike up a conversation because I do know them but, I was shy. Then I saw them trying to get their message through 'sign language'(not the proper one; it was more of body language), using their hand movements and lips movements. Stupidly, I assumed that they were addressing it to me and I replied to them loudly (I should have minded my own business...). I actually thought that they were asking where were my brothers. A while later, I realize that they were not looking at me. They were looking over me. Their sister was sitting right behind me (about two steps away) and I did not realize.

However, when I did realize, I tried to cover up by looking over the boys. I shall tell you, it was not that... embarrassing when I realize that they were not talking to me. What came later is much embarrassing than that. I saw my discipline teacher sitting at table a feet away, watching me the whole time. In my head, I imagined to lock myself in a cupboard and never come out ever again. I swear I saw that woman holding back her laughter. IT WAS SO... EMBARRASSING!!!