^^ What he said. A good way to make sure he knows you do smoke weed is to bring it up nonchalantly in a conversation like, "The other night, Joe and I were smoking a joint in Joe's garage, and I saw his dad's 1967 Corvette. It was pretty cool."

Then, your friend will either ask you to confirm that you said you were smoking weed and will either get upset or not have a problem with it.

More than likely he'll just take it in stride and not care.