904
xkcd #2929: Good and Bad Ideas
(imgs.xkcd.com)
Alt text:
While it seemed like a fun prank at the time, I realize my prank fire extinguishers full of leaded gasoline were a mistake.
Never had them not work in cold. They change even during heavy snowfall when it's well below freezing and well, no sun, heavy clouds. It's great because they help with the glare from snow.