I suppose there's worse ways to go crazy than have your mind repeat the "One Pound Fish" ditty incessantly. So far, that hasn't happened to me. But it could...
Be warned. If you're prone to catchy songs playing uncontrollably in your head, don't watch these videos.
(Assuming you're one of the few people in the world, which included me up until a few days ago, who hasn't seen them yet.)
Background story here.
This is the original video of the fish seller.
And this is the jazzed up post-viral video version.