england:slang term for rolled-up piece of cardboard put in the mouth end of a joint to catch tar which is produced by tobacco rolled in the joint.
america:usually means the end of a joint which can be re-used because there's still some weed in it. this occurs because in america, joints aren't rolled alot with tobacco and so don't need a filter.
not related to weed: a small freshwater fish.
-dude, you rolled this roach way too tight, i can't smoke this shit.
-well next time roll your own fucking spliffs, you retard.
-sir, we found marijuana roaches in your apartment
-so what, i smoke pot, what is that a crime?
-i just caught a roach!
-wtf are your on about?
-the fish, you fuckhead