Occasionally, when I put my Samsung Galaxy S3 down relatively firmly, it makes a noise that's sort of half way between 'BONG' and 'CLANK'. When it happens I can immediately pick it up and put it down again to make it happen again. I can repeat this for as long as I like. Pick up, put down, BONG/CLANK, repeat.
There are no on-screen messages, just the noise. Why is it doing this? Can it be stopped?