Is my friend being rude, how should I confront him?

Here is the link.

I have a friend that likes to go to public bathrooms and hide in stalls and imitate very loudly the noises that other people make in the bathroom stalls next to his. He even records these noises (his imitations and the other persons authentic ones) and posts them on an internet site.

I think this is going to far. How do I bring him back to earth?

Here is the link.