According to "Happy Hour is for Amateurs" by an anonymous lawyer, a polar bear is a subtype of single woman at a bar, waiting to be picked up. Polar bears are large, white, have a thick layer of subcutaneous blubber, and hunt men for sport. They rarely see an opportunity to move in for the kill, and thus never pass one up. They tend to have exclusive territories, and it is rare to see multiple polar bears prowling the same bar, due to their inherently competitive nature and the scarcity of men drunk or desperate enough to take them home.
See also: hogging
, last call
, beer goggles
, sidewalk sale
"Looks like Anna found her ride home for the night. We raise our glasses to another hapless victim of our local Polar Bear."