mine broke in bed in the middle of the night....
i had a towel under the sheet from about 36 wks (must add that to the to do list) and also sat on one in the car...
I also have these visions of being out somewhere - not much you can do if it happens - and i think at the time you will be more concerned with other things to be embarrassed but i think a fear we all have. makes a good story thoughto look at the positive side.