What is a polite and non-confrontational way to ask a stranger for their used MUNI transfers?

When I'm getting off the bus, and I have a transfer that I just plan on throwing in the trash, what I usually like to do is look for someone with money in their hands and offer them the transfer so they can save themselves a couple bucks. While I understand the skeptical looks that I often get, it's hard for me to deal with the fact that it's assumed that I'm going to try to sell them something. It really is annoying. But that's a whole separate trip.

Here's what I'm wondering. Just as difficult as trying to give people in this city something for nothing, is trying to get something for nothing. When I give a stranger my transfer, it is almost a way of acknowledging the shared experience of taking the bus--as if to say, "We don't know each other, but here we are; now let's make the best of it." So I guess it's a little bit more of a downer when I come at it from the opposite angle--namely, one of needing, rather than having, one of wishing someone would see it fit to give me a transfer. I mean, why not? And why is it so hard for me to just come right out and ask? Anyone have a suggestion for how I might go about asking this?