If you like Kidney Stones. 
That's what the EFF i'm talking about.

Had 2 kidney stones in 98 and 99, and last year had another.. had to call an ambulance at my work, they thought I was dying. Turned out to be a 1mm stone that had mode it almost all the way through, got stuck just before my bladder.
Passed the stone, all is well, right?
Wrong.
x-rays said there is a 10-15mm stone win my left kidney.... tooo big to pass. Three procedures later, they operate... some midevil torture stuff, man, I'm out of work almost 2 weeks....
I don't drink tea anymore!