Someone who insists on keeping the air conditioner turned on, even in the middle of October. They love keeping their dwelling place noticeably colder than the air outside, even on an already cool day. Known to cause great frustration to room mates who are much more comfortable with normal temperatures.
Bob: Jeez, why do we have to wear sweaters in here!? It's 76 degrees outside!
Fred: Sorry, Jordan is a bit of a polar bear.
Slang term usally heard on trucker's CB channels, used to informed other truckers of the presence of a police officer (CHP). Polar Bear get the name from their white unmarked patrol vehicles.