I don't know what to say to this...

[Scowl]

By motherfucking Zeus, does anyone know if this is really her? Did she really do this?

Avril Lavigne singing in Mandarin:
http://www.youtube.com/watch?v=_N13DLrRdr4

I don't understand Japanese, but if you do then perhaps this will bring you some pain:
http://www.youtube.com/watch?v=c6YhaDA6fNc

[Liang]

It sounds sped up and altered so I doubt it.

[evil_FUX]

^Nope it's genuine. Posted on her myspace and downloadable on iTunes. She also reaches into, Japanese, french, german,..

[Televangelist]

Well... I just skipped around the track a bit, but her Japanese doesn't sound awful, at least. She made an effort to get the syllables right, get that half-l half-r sound down, etc. Better than some freakish anime fan running around going "DESU DESU DESU".

A lot of American singers have done Japanese versions of their songs, or at least more than you might think. Ben Folds Five's "Song for the Dumped" pops to mind.