You could say something along the lines of:
"Hey, Friend, what's so good about weed? Why are you always smoking it?"
If he's smoking it for medical purposes, then just drop it, but if it's illegal and he's doing it to "look cool", then I would further ask questions about it.
No you can not eat poop. It is waste and full of disease
I haven't heard of PRICES method. I only know of PRICE which stands for P - protect
R - rest
I - ice
C - compress
E - elevate
However, since we are dealing with injuries, S can stand for SPLINT. You apply a splint on injuries with broken bones. This is to ensure that the edges of the broken bones will meld and mend together without any difficulty.