Describe your most awkward/embarassing moment in a social situation?

I've done the classic walking into a lamp post on a busy high street whilst being distracted by something on the other side of the road. I've also had my dog pee on my leg whilst I was talking to someone on the street. Then there those awkward moments when yuou are desperate for the toilet but you are engaged in a conversation that you cannot break away from with your boss or some other official. Excruciating. I always wonder if my facial expressions give me away as I wince and go through hot and cold flushes right in front of them. Hmm. So what's your most awkward/embarassing moment in a social situation?