Mobistar, a belgium phona company, is famous for its lousy customer service. A good reason to get pranked :-)

The pranksters proceed to put the Mobistar employees through a high-art comedic phone hell, disconnecting them, subjecting them to terrible hold music (performed live from within the container on a little synthesizer), gradually ratcheting the misery up in a Dante-worthy re-enactment of every terrible, awful mobile phone company experience. 

The program was a huge hit in Belgium (be sure to watch it all the way through for the a killer punchline), and has been captioned in English for those of us in the anglosphere to enjoy.