Serious answer.
The internet is made up of thousands and thousands of computers all over the world. And the information on the web (web sites and web pages) are stored on all those thousands and thousands of computers.
In many ways it is like the telephone system. When you pick up your phone to "dial" someone your request is sent via lots of wires and telephone exchanges to the actual telephone you want.
Same with the internet, every time you want to visit a web site, then your request is sent via lots of wires and computer servers to the computer holding the web site you want.
The web site you look at may be on a computer in England or Australia or America or China or Brazil and so on.
So to answer your question to cant "turn off" the internet.
However you could stop people getting to the internet by removing their access to the actual wires (cutting them), or access to the computer servers that "route" them to the web sites.
During the recent problems in Egypt the authorities cut off access to the internet to stop people finding out what was going on, so in their case the internet was "switched off".
http://www.guardian.c...s-off-internet-access