I carry around some unfunded paper bitcoins in my wallet and saw the bell ringer and was "this close" to pulling one out, funding it and dropping it in the bucket. I didn't have a pen to write instruction on how to redeem it so I passed on the opportunity. I don't know what they'ld do with it -- maybe they'ld claim it. I'ld write that it expires in 30 days and then check. If they didn't claim it by then I'ld redeem it and give it to someone else.
Name any other form of money you have that level of flexibility with?
Hmmm, I hadn't though of doing a time limited offer like that. Nice idea.