I had a friend that would get together with us every night and roll two or three blunts and share them with our group of 5-6. He never asked us for anything in return.
You can expect that I did him a lot of favors, including driving him home from Long Island into Brooklyn, or smoking him out every single time I picked up. If there's one thing I can't stand, it's a weed hog... so I go to great lengths not to be that person.
I have this one friend... she's REALLY straightforward. "So...uh... are we going to smoke tonight?" Sometimes, when her stash is low (mine never is) she's like, "I can't share tonight." And normally I'd have no problem sharing, but I know she's expecting it. When I'll give her a look, she'll be like, "UH. You are sharing with me, right? Because your stuff is cheap and you can get it WHENEVER you want. You have SO MUCH." I hate that shit.