Salamanders are the source of all Evil in the Universe. They are vicious, cunning, and cruel. They are also extremely hard to see. Very often, when you have a particular run of bad fortune, it's because one or more salamanders are actually clinging to you.
Squirrels, on the other hand, are the sworn enemies of the salamanders. They may or may not care for goodness, nobility, and humanity, but they definitely oppose the salamanders and all their works.
So when you're walking under a tree and a squirrel throws a nut at you, he isn't trying to hurt you. He's trying to knock the salamanders off.
This is the kind of religious revelation that comes to CoSci Majors after a long night in the computer lab. (And yes, that's exactly where it came from - I can't claim credit for this one.) It is best explained in a tone of wide-eyed sincerity, preferably on a Saturday morning when someone has come knocking on your door to find out if you've heard how wonderful their particular religious beliefs are.
Seriously, try it out the next time you get the opportunity.