1. Someone who plays in the snow or sleds during the ski season instead of doing a real winter sport ie. snowboarding or skiing
2. Someone who drives all the way up to the pass so they can play in the snow, usually annoying to real snow-sport participants, usually takes up alot of the good parking so snow-sporters have to walk extra far with heavy equipment.
"Dude. There's no place to park up here."
"Yeah all the snow rats took up all the fuckin parking spots!"
Someone who is into winter sports and tends to go to the mountains often. Experienced skier/snowboarder.
"Do you want to go to the pass next week?"
"Yeah man, I go every week."
"Dude, you're such a snow rat."