Uhm, weird, gross, funny, whatever you want to call it, it's a sure thing in Japan where they're selling environmental-friendly batteries that are powered by fluids...and that means any fluid, including your, yup, urine. Yup. Pee.
"The basic principle is that a mixture of magnesium and carbon reacts when mixed with a liquid to produce, in the case of the AA battery, up to 500 milliamp-hours (mAh) of life."
Not bad for batteries, I have to say...but pee? Naw...I'd just rather throw them out...I mean, what if I get pee on my hands?!? That's gross!! =P