OK, I know that the Mythbusters didn't invent this idea, but that's where I heard about it.
Step 1: Have Some Rusty Chrome.
I'm sad to say that I've been a bad daddy to my little bike. These pipes were new a few years ago. The originals were completely rotted out, so I got these replacements on e-bay. Par for the course with aftermarkets the chrome ain't that thick.
It doesn't help that I haven't so much as pulled the cover off for weeks at a time.
Step 2: Supplies!
You will need:
"Cola" - I used Wal-Mart diet cola. I'd heard that diet is less sticky. 54 cents for 2L.
Step 3: Pour 'n Scrub
Pour the Diet Coke on your rusty chrome (is there any better use for this stuff, lacking Mentos?) Crumple up some foil and use it to scrub the nasty rust away.
Rinse with warm water and wipe dry.
Step 4: Gawp at the Results.
I was really blown away. In some of the pictures the flash makes it look more scratchy than it really is. I don't think I'd use this on a top dollar bike, but I hope a top dollar bike would have better chrome (and better care).