As far as christmas songs, Carol of the Bells. I just hate it. Its too creepy sounding to be a christmas song and honestly it scares me.
I am a huge Offspring fan, but I can't stand Self-Esteem. I know its the song that broke them and one of their biggest hits, but I just despise it.
Also, anything by Nirvana. I find them so ear shatteringly horrid that it is physically impossible for me to listen to more than two seconds of any song