I couldn't afford anything except the diapers (but I already own a full footed sleeper) so I wet my sleeper right outside the store, went in and purchased diapers like that. I got some
weird looks, but no one there would recognize me. (also, I did this like 30 miles from where I live, in a drug store where no one would recognize me)
Kirst1, you have put on a big diaper (or 2 or 3 to make it big and puffy) and a skirt short enough so that it's just peeking out and it will definitely be visible when you bend over. Go to a local store to pick up some baby wipes, when you get to the check out, have a look of desperation on your face, grab your crotch and mention (loud enough for the person behind you in line will hear you) that you need to go to the bathroom and excuse yourself. Then sprint to the restroom so your skirt will be flying up. What you do after that is up to you.