WHAT A GREAT IDEA......I must try it sometime too....
That's funny because I have always wanted to tie a guy up naked and leave him some place in public where lots of people, mostly women would find him but instead of coming to his rescue, they all stand around and laugh at him and make fun of him for wanting to be tied up naked in front of other people.
OK I've got something to confess. A couple of years ago I did this at a sex club to a male friend of mine. It wasn't exactly public but his erection told me that wasn't important. The important thing is that a bunch of people got to see him tied up naked and helpless and some even tormented him which was fun. But I would really love to see a guy in the kind of predicament like you described.