For me, it would have to be "Oops...I Did it Again".
That song was on Britney Spear's album from 1999 but I first heard it when they started playing it on the radio regularly in 2000 and then made a music video for it. The song made no sense but at the time I was 13 and I was happy with my life. As for most annoying song, it's hard to say. I liked or tolerated many of the songs from the 90s and early 2000s but once 2002 or 2003 hit then I would hear 50 Cent's "In Da Club" over and over again. It was insane the amount of times I heard it on the bus going to school and it was torture.
Willow Smith's Whip my hair. Damn that song is annoying as hell. It's like listening to a damn car alarm. I think that was the beginning of Will Smith forcing his obnoxious trouserstain kids on everyone.
That song is hilarious. You know he's a comedy guy right?
Yes, I know who Liam Lynch is. And even though I liked the Tenacious D movie I still find this song annoying as all hell. Everyone used to talk about how funny it is but there's only a few parts that made me chuckle.
Another song that kills me is this cover of Pink Floyd's Comfortably numb.
The class is Pain 101. Your instructor is Casey Jones.
This 'thing' right here is just a huge abortion. Hank Williams, George Jones, Johnny Cash, and Waylon Jennings are all collectively rolling in their graves due to this being labeled as 'country music'.