What is the most potent earworm you can think of?

From Wikipedia for those who don't know what an earworm is:

An earworm, sometimes known as a brainworm, is a catchy piece of music that continually repeats through a person's mind after it is no longer playing.

For me, it's Spice Girls. I have never, ever enjoyed their music even in the slightest, but every now and then I get "If you wanna be my lover" stuck in my head... as it is now gosh darnit.

I always used to get the chorus of Jacqueline by Franz Ferdinand stuck in my head while I was at work. Considering that the lyrics are It’s always better on holiday, so much better on holiday, that’s why we only work when we need the money there's a certain irony to that. Not so much lately though.

Oh I have so many. I even wrote an entire parody about getting songs stuck in my head. Don't Play (That Darn Song)

-Eurhythmic's "Sweet Dreams" (because I typed this I will be singing this for the next week)
-Eddie Money's "Take Me Home Tonight"
-Jana Kramer's "I Got The Boy" (I listen to country sometimes. This song has invaded my subconscious lately. So obnoxious)
-Walk the Moon's "Shut up and Dance" (okay I actually love this song, but it's starting to get overplayed. Also my sister plays this album in her car so all of those songs were earworms when I was riding with her over the holidays)
-Anything featuring Ellie Goulding
-The Killers "Spaceman" (and probably a lot of their other songs, too. I actually love this song as well, it just sticks a little too much)
"I Don't Mind" by Juicy J/Usher (this is a proper earworm, as I actually detest the song)

I'll stop there.

And Nate, you're not alone. Wannabe by the Spice Girls is the catchiest song of all time, according to science. Fun fact, I actually played those games but my reflexes are way too slow so I dragged the data down.