Well contrary to what I always thought, being that snakes constricted prey so they couldn't breath, is actually not 100% true. They actually constrict to the point of circulatory failure, which means that their prey's heart can not pump blood around due to the constricting force the snake puts on them. This kills them faster than simply just reducing the blood's oxygen level to the point of death.

In other words.....I would never want to find out what that feels like.