sphinxie talked about her most embaressing moment and it set me to thinking about what constitues embaressment
I think there needs to be a decidedly public element. The first thing that lept to my mind was an event where I was college and walking accross campus and had a sudden uncontrollable bout of diarrhea, I happened to be near the gymnauseum and was able to get to a set of unpopulated showers and clean myself and my clothes. But I don't think that really counts as embaressing because no one saw me at the time and I don't think I ever told anyone about it. I didn't find the odd looks I got from the bus driver & passengers from riding home sopping wet one a hot summer day that embaressing compared to what it could have been like, so while that's unpleasent or even disgusting I don't think it really qualifies as embaressing.
I think embaressing also needs an element of hubris, having your pride or ambition handed to you with side of crow. I know there have been dozens of times this has happened to me but my mind skitters away from recalling the details of any particular instance. I have a hazy recollection of spouting fulsomly and aggrandizingly on some subject at a party trying to impress a cute chick and having her quietly and politely correct me with much more real expertise (maybe I was going on about law and Monica saying something like "Well in Law School...").
I suspect a lack of embaressing anecdotes indicates that you haven't been as publically dramatic, expressive, and assertive as you could/should be, that you are being too shy.