The multiple(!) ice cream trucks that come by everyday and their infernal insipid muzak. One of them plays "Yankee Doodle" and the other one plays some ditty that I cannot remember at the moment but will almost certainly be stuck in my head by the end of the afternoon (driving out the Theme from the Flintstones, which is stuck there now).

I wonder if one can listen to Handel preventively to protect against such earworms, or whether I should just have the CD queued up and ready to go after the fact to drive them out. I believe an experiment is called for.