I used to do this when I smoked. Go buy yourself a pack of Camel Crush Menthols. You know the kind with the little bead in the filter that you crush to make it fresh menthol? Yeah, those. You see where I'm going with this, right? You rip the filter off the cigarette. Smoke the cigarette as you please. Then roll a joint with the filter. Eh? You crush it, then light the joint, and huzzah! Mentholated marijuana. Now before you say, "Oh, but you're filtering the weed and won't get so high." Well shut up. Two things. One is if you're rolling joints, you clearly have weed to burn. Second, the filter only catches the heavy carbon molecules, not the actual THC itself. So do it, have fun. Also, dissolve a jolly rancher in your bong water for some extra flavor.