I've had plenty of embarrassing moments.. but I can't think of the most awkward. Probably that time I was talking shit on some girl and she was right behind me. I can't remember what I said.. something about her being a hoe.. then I noticed her and glared at her. She had been a rude skank to me and my friends and deserved it, or so I thought. She started crying and said something about because her Dad didn't love her. I was like o_____________o and shut up after that. I felt kinda bad.. awkward.
That has happened to me too. x.x
From the past year:
I went to a free concert showing of The Strokes for SXSW and this drunk lady bumped into me and spilled beer all over me. It turned out to be this teacher from my school. She isn't my teacher, but I always go into her classroom because she was one of me friend's 8th period teacher. It was hella awkward when I would walk into her class after that. We never talked about it though. I really hope she doesn't remember.

Another time I went to this rave called Spring Love, and I bumped into one of my friends. She was rolling, but that wasn't surprising. But she was with a group of friends and one of the people was this kid in one of my classes. Apparently he was on a heroine based roll and he was tripping hardcore. He honestly looked like a velociraptor walking around, not to mention he needed people to guide him around. He walked up to me and was like, "hey, I KNOW YOU!"
When Monday hit I tried my best to be late to class (since my class before that is really close, and me and that kid tend to be the first ones to get in). I was really late, but when I was walking to the door that kid walked in at the same time. We had one of those moments when you're waiting for the other person to go, then you both go at the same time. It was pretty awkward. He kept trying to make eye contact with me throughout the class though. I bumped into three people from that class at that rave. xP
So, don't really have that much of an awkward life, but those were this year (2011).