Why is it that when you get a song stuck in your head its the last one you would ever want?

It seems to be a song I can't stand and I don't even know how it got there. I would rather listen to 100 cats trying to hang on to a chalkboard than hear " Benny and The Jets " play in my head again. Hate the song, don't like Elton John and sure as $hit don't know why it's playing over and over and over....I'm sure I didn't hear it today on my travels. Why isn't it ever a GOOD song?B-b-b-b-benny and the jets..".Excuse me officer! Yes, up here! I have a concealed weapon pointed at you! You have no CHOICE but deadly force. SHOOT MEE!"