Ha! I heard about this one too. And I did considered doing it. What you read on the net is that urine is not the ribish of the body and that is full of noce hormones and minerals that maybe you are not absorbing well and that it has all that you need bla bla bla.
At the end I didnt try it so I dont know if these claims are true but if you google it you will find tons of people that swear by it. Many of them from India.