Don't know why, but I can't help https://www.youtube.com/watch?v=3hvqFZzbV24for some reason. Though i've heard the original song from the TV series openings, it seems the movie theme song is just better. I won't outright singing it since my voice is horrible, but i'll definitely lip sync sing to it.

[censored] pony songs.

This.

Also I tend to find myself attempting to sing along with opening themes to anime, especially though http://www.youtube.com/watch?v=3TdKnncFHQQ, the opening to the 3rd season of Naruto. Not sure why though, I just find it catchy.

Ya da da dadada dada afro Dadadadada da circus.....

And Hot Cross Buns is stuck in there write now thanks to my desk being outside the music classroom ... damn recorders!

Others:

I'm Gonna Be (500 Miles)
Brown Eyed Girl
Happy Birthday
Friends in Low Places
In Heaven There Ain't No Beer

some of them are sung whilst you're out and drinking, and the whole bar sings...ya gotta sing along!

Black Hole Sun.

Always sing it. Always.