Maybe you've heard: Comedy Central's Jon Stewart is holding a "Rally to Restore Sanity" next week. His fellow satirist, Stephen Colbert, will be there, too, leading his "March to Keep Fear Alive." This is all going down on the day before Halloween, right on the National Mall in Washington, D.C.

Jon Stewart's not a politician (yet), but I suspect he'll get more people -- especially young people -- thinking about how politics work (or don't work) in this country than any elected official could. Stewart says the goal of his rally is to "take it down a notch for America." Sounds reasonable. Of course, with Colbert around, you can be sure things won't get too reasonable. This is the guy, after all, who once serenaded my predecessor, Carl Pope, with a suicidal black bear hand puppet.

I won't be in D.C. that weekend (my kids care more about trick-or-treating than they do about some guys wearing suits on TV). But plenty of Sierra Club supporters will be there and to be sure they're properly attired, we're printing some t-shirts to mark the occasion.

We're taking suggestions for both "sanity" and "fear" messages to put on the shirts, and we'll use the best ones. Give us your smartest (or funniest) ideas by midnight Friday, and you might win a solar-powered backpack. A few that have caught my eye so far :

* Mountaintop-Removal Mining: Keep the Earth Flat
* Sanity: 100% Renewable.
* I don't like polar bears anyway.
* Save the Earth! Because the thought of domesticating another planet is just exhausting.

Although I won't be there, I hope Jon Stewart achieves his goal. I'm a big fan of sanity. Polluting the air we breathe and the water we drink is just nuts. And when our economy is pulling itself out of a ditch, it’s also a bit batty to stifle investments in solar and wind that would put more people to work than any coal or nuclear plant out there. And I'm happy to argue about how we should deal with runaway greenhouse gas emissions, but shouldn't we all be able to agree it's a prudent goal? I mean, even if you did have doubts about the reality of climate disruption (because you somehow knew more than the best scientists in the world), why not hedge your bets?

So put me down for reason, sanity, and common sense (and just a little bit of fear for the possibility that one day it could be me sitting across from a guy in a suit with a hand puppet).

Image: Some rights reserved by D.C.Atty