Idea: Designer signs for beggars and bums

Designing signage seems like it would be a lot of fun. Whenever I see things up on the insides of BART cars, I always think “So many people see that everday, why didn’t they do a better job designing it?” The answer is that BART probably can’t afford decent designers, but that’s besides the point.
Anyway, I got thinking about a way that signage I design could see some good crowds, then I remembered an idea my brother Cameron had about advertising the company we work for, HubPages. There is a bum that hangs out around our office building. Hundreds of people see him everyday, so if we gave him a shirt that said “HubPages.com”, then it might prove to be a good way to stretch our advertising budget. Especially considering he only has the one shirt.
The problem is, bums get dirty, and who wants some vagabond wiping his butt nose with your logo? So what’s the thing vital to the begging industry, that no self respecting bum would treat harshly? Their sign. So here’s my idea. Get the signs printed on sturdy poster board, put your URL at the bottom, and distribute to bums in high traffic areas.
This example isn’t as designed a real Designer Bum Sign would be, but just to illustrate the point.
Or you go with something a little more timely. Why not?
Any thoughts?
How about ‘If you look at me, you owe me $1 (gotcha!)’ or ‘I only accept non-sequential, unmarked bills’.