in a very old thread someone mentioned putting folded flyers in the place where you fill up with gas. that way the person would be alone when they got it.
It would seem that if they all came back at the same time and saw the flyer under the wiper then herd mentality might kick in and they might garbage them right then and there or an elder may take them off first.
I don't know if this is legal and I know some gas filler compartments are locked but some still open from the outside.
hoser