Lovefool by The Cardigans, because, 1) I grew up in the nineties. And 2) Much to my horror, a rather famous singer (that is not well liked on the Internet) sampled it. And my sister was listening to the song that sampled it, and while I will defend this man in some instances (even the worst music has some fans), I could not let his butchering of the song remain in my head.
Okay, so Lovefool by The Cardigans.