5PM edit: I came back an hour later and there was $4.85 in the cup. Should Rubber Duck consult a lawyer before we move to a more popular beach? The overhead is dirt cheap. A few breadcrumbs, maybe a fish rack or two.
I stole the concept for this idea from XKCD comics and forgot to atribute them. They are math nerds who make you laugh with equations and other science stuff. I usually wet my pants when I read them. The seagull one was just weird.