Dogs are the main culprit here, although cats and a few other small animals shift their ears around on occasion. But whenever dogs hears something super sweet or super lame, they lift their ears up as if to say, "look what I can do with my ears, humans. Can you do this? No, you can't. Aaawww, that's too fucking bad. Oh wait, you can wiggle your ears a little. Neat party trick, but you can't completely change their angle so as to gain significantly better hearing, can you? No, I didn't think so. Also, how good is your hearing anyway? What's that? I couldn't hear you. Just kidding, I could totally hear you whispering, 'my hearing is really shitty compared to yours, dog, because you have such great hearing, dog. You're the best.' Listen (if you can, with your crappy immobile ears), if you rub my belly and take me to the park, I wont tell anyone about your shitty hearing, okay?"
At least that's what the ear raise says to me, but I may read into my pet's actions too much...nah, I don't. Not at all.
(flickr photo Bat Eared Dog shock by :mrMark:; http://www.flickr.com/photos/what_i_see/147122825/)