Also, communion is an actual part of Christianity, whereas I think "Hindus drink their god's piss" was just a complete fabrication.

I suspect this is pointing to the Hindu reverence for cattle, which tends to show up in weird ways in Hindu-Muslim disputes from that area. Milk is not urine, and cows aren't treated as gods per se, but it's an allegation that I could see Kevin Baconing its way out of the truth.

I do know of one case of ceremonial consumption of urine, but it's not Hindu -- it's a Siberian entheogenic practice aimed at the still-psychoactive metabolites of compounds found in the A. muscaria mushroom, previously eaten by shamans.