Sharks are interesting creatures, and in more recent times it’s been discovered that they like having their noses rubbed, which can lead to a state of hypnosis or ‘tonic immobility’. They can also go into this state when turned upside down with shark researchers often taking advantage of this physiological phenomenon when studying these animals (see the guys on the Discovery Channel working on Great White Sharks).
This is believed to occur because of the vast number of sensory pores in the noses of sharks, called ampullae of Lorenzini, which are used to detect electric signals from muscle movement in animals around them. These sensory organs are overstimulated when touched and lead to the shark falling into a state of ‘tonic immobility’, whether because they enjoy it immensely, simply become temporarily paralysed, or otherwise I’m yet to ascertain. They can remain in this state for up to 15 minutes.
I did a quick search on Google.com and it lead me to a video on YouTube.com that turned out to be this same guy doing this with these sharks.