If you had to choose a single song to play on infinte loop for the rest of your life...

[Cuniculus]

You Can't Always Get What You Want - Rolling Stones. It's a good reminder of how life really is.

 

[Lyri]

This!

 

[oliveira8]

You Can't Always Get What You Want - Rolling Stones. It's a good reminder of how life really is.

But sometimes you get what you need!

 

[General Vagueness]

Probably something without words.

Handel's Messiah
It's over forty-eight hours long.

I'm not very familiar with it but that sounds like a good for this. Keeping with instrumentals, near the top of my list would be the Halo theme by Marty O'Donnell and one of the main themes from StarTropics by Y. Hirai and completely abandoning instrumentals I'd say "Still Alive" by Jonathan Coulton or just maybe "Blue" by Eiffel 65.
EDIT:

This!

How could I forget? Also high on my list for this would be "Technologic" and "Harder, Better, Faster, Stronger" by Daft Punk.

 

[EscapeGoat_v1legacy]

totally Cantina Band by John Williams

What an awesome song that'd be on an infinite loop.

Otherwise, I'd have picked something like this:

Spoiler

 

[OniSuika]

http://www.youtube.com/watch?v=Vnx1e8oO8LY

Fragrance Of Oriental Sunflower, by IOSYS

 

[FalloutJack]

I've got a lovely bunch of coconuts... [http://www.youtube.com/watch?v=bGSWH66FpA0]

 

[Maze1125]

This one [http://www.weebls-stuff.com/toons/annoying/]

 

[deleted60525]

DELETED

 

[blipblop]

http://skybert88.deviantart.com/art/Yahtzee-Caramell-dansen-99626883

Maybe it'll drown out the voices.

And if not, I'll shortly be insane, so it won't matter anymore.

hehe I´v been listening to this song all day

 

[Sampler]

http://www.leekspin.com/

 

[GRoXERs]

John Cage's 4'33". Four minutes and thirty three seconds of silence.

You are clearly the only person thinking this through. I concur.

 

[Salem_Wolf]

[link]http://www.youtube.com/watch?v=zuyupBmHfVQ[/link]

I could probably stand this song the rest of my life, or kill myself after it's played 10,000 or so times.

 

[JC175]

John Cage's 4'33". Four minutes and thirty three seconds of silence.

Exactly. This would be the most sensible option, as no matter how good a song is, it's going to drive you insane if you hear it continuously for the rest of your life.

Somebody give this man a cookie!

 

[blipblop]

I would probably shoot my self if I only could hear one song for the rest of my life
that or separate my ears from my head

 

[BoxCutter]

Breaking Ties by OceanLab

 

[Salem_Wolf]

http://skybert88.deviantart.com/art/Yahtzee-Caramell-dansen-99626883

Maybe it'll drown out the voices.

And if not, I'll shortly be insane, so it won't matter anymore.

Ah...crap. >_<;

Well this is my song for the rest of the day...

 

[BaronXS]

John Cage's 4'33". Four minutes and thirty three seconds of silence.

Haha, I wasn't expecting that! Well played, sir.