Most Favoritest Song of All Time

Word up to my peeps. I just recently joined another social networking site (I don't know if I could handle anymore) called Blip.fm. Basically, it allows you to search for songs and post them with a comment so other people can see. This made me start thinking. What is your favorite song of all time? Post your comments. My favorite song will come, but I'll have to think about it for a while.