The freakin' Unicorn Song makes my whole body hurt. I detest it. Close on its heels are Margaritaville, Brown-Eyed Girl, and (bravely, now) Whiskey in the Jar.
You'd think I worked in an Irish bar that caters to tourists, huh?
One of the Irish pub players I know gave up the Unicorn Song for Lent one year and refused to play it during that time. He came back months later, and sure enough someone requested it during the first set (people's love for this song truly astounds me). He told the requestor that he had given the song up for Lent and enjoyed it so much that he had decided never to pick it up again. And I've never heard him play it since.