It depends. Is the snake poisonous and if so, some animals are immune to the venom of a snake bite. Would the kangaroo be one of those lucky few. And what kind of snake is it? Take for instance, the anaconda. Not a poisonous creature but can be massive and of course, extremely strong. One defends itself while vertical and the other while horizontal. This encounter may happen, and no doubt does, but I'm willing to bet both go out of their way to avoid the other. These questions raise even more questions and since I'm not a learned individual when it comes to the animal kingdom, I'll leave that to the experts.