> We used to make jokes what if a TP user have diarrhea, how many trees will that be ?

Diarrhoea is pretty much water, so it cleans up with paper very well.

> If a bird shits on your hand will you use paper or water to clean it ?

That's a misleading analogy. Do you eat off your butt? If I got bird poo on my bare foot, I'd wipe it off in the dirt and move on. Most people shower every few days anyway. I don't care how clean my butt is, just as long as it doesn't smell and it doesn't itch.

(FYI, in English, a space is only used after end-of-sentence punctuation, not before. I've never understood why Indians consistently get this wrong.)