So at some point before the wedding I picked up a Fred Meyer plastic grocery bag underneath the BMW, which subsequently melted itself to the exhaust system and smelled all the way to Canada.
Being lazy and on my honeymoon, I didn't actually remove the plastic until the last day of the trip—which meant I left a burning-plastic smell throughout Victoria and Butchart Gardens.
That said, I did pull most of the plastic from the car on the last day in Canada, but the @#$!ing thing still smells to high-heaven, since I didn't get a chance to actually scrape it from the exhaust pipe.
Ugh.

I was riding my motorcycle on I-25 in Albuquerque when a plastic bag hit my motorcycle. It stuck to the pipes and ruined the chrome. I'm told you can take them off with oven cleaner.
Yowch. At least I didn't have to worry about the finish on the fore end of my catalytic converter.
Good call on the oven cleaner, though—I'll hit that up shortly.
Let me know how that goes for you. I've been hesitant to try it on my chrome pipes.
Last week at karaoke night I was told in no uncertain terms that my pipes are absolutely not made of any precious metal whatsoever.
I'd be happy to try the oven cleaner and report back on the findings.
*cough*