I don’t go on social media so I don’t really get it but I have seen memes here and there of women getting mauled by bears presented in a “heh, serves her right” kind of way.
So weird that dudes complain that they can’t get women when the message they put out there is they hate women and make images of them being brutally mauled. 
EDIT: I did not expect to see people I trust minimise SA here. I’m disappointed, that’s something I expect from a random chud blowing in from another instance, not you guys. Most of you were extremely cool in your answers, but to the one or two that weren’t. Do fucking better.
Play dead until you aren’t playing anymore, basically
For a polar bear or mountain lion, however, by the time you see it, you’re already dead. It already knew you were there, and specifically decided that it wanted to be in your presence.
Never do that useless it’s actively killing you. Yell at the bear like you would with a black bear and if that doesn’t work, use bear spray (bear spray is the answer most of the time). If a brown bear attacks and knocks you down, that is the one acceptable instance where playing dead is a half decent idea.