When I was in high school,when me and my buddy would smoked a joint,we would put it in the dirt and say stuff like "Give it back to tha land" as we did it.
I also remember a period when I used to burn wid my cousin and we would smoke until there was a good size roach,like big enough to get you high by yourself, and we would put it in the match box with the crutch(back when I had this thing for lighting my weed with wooden matches)
and we would leave it on the bus stop bench or wherever we were burning and Tag up the box with our sign and leave a message for the person who found it.You know,maybe some lonely guy would find it and burn it.We actually met some chicks that were lookin for the guys who been leaving the weed around.We was burning and these chicks just walked up and we smoked them out and they started talking about how they found a matchbook with a half joint in it and they smoked it and me and my cousin just looked at eachother and smiled.We never told them it was us,but we did end up partying with them a few times.
But nowdays I just save them and add them to my next joint,unless I run out and I pack a bowl.