My iPhone 3gs won't play the full song

I'll be playing the music that's on my phone, and it doesn't play the whole song, it cuts it off somewhere near the end! Why is it doing this, and how can I get it to play the whole song?

It's an iPhone. Answer: Get an android. I'm serious. I'm not trying to be a missionary, but seriously. XD

It's a corrupt file that you downloaded onto your iPhone.

Go to iTunes, delete the song from your library then redownload it and then resync the iPhone.