I once had to ride on a long trip with a young teenage boy in the van who played the opening riff from Deep Purple's "Smoke on the Water" on his guitar for, I swear it felt like, FIVE THOUSAND MILES. When I complained, after the 789th time he played it, his adoring mother insisted that he had the right to "enjoy himself on the trip". So, I got to hear it for the next 789 times.
Even though I love that song, the opening riff is like fingernails on the blackboard to me. I twitch. And itch.