I've known guys that have gotten stuck out in major winter storms who have had to either kill one of their cattle or a moose or a bear (I forget which the latter two was up in Alaska) and crawl inside to keep warm. I've slaughtered and butchered enough livestock that I don't think it would bother me any, particularly if my life were at stake. But living conditions would have to be pretty rough for me to use that method to cross the border. But then, I suppose that's why people do it. We're pretty spoiled, and we often forget it.
I liked the ones about the guys who commandeered Migs and flew to safety and the guys who rented the cars (Austen Healys I think they were) and slid under the Berlin Wall. Pretty cool.