greb stain
A green residue that is left by a greebo. It is usually found on a wall because of its sticky nature. You should never touch a greb stain unless you are a greebo because it could have unforseen consequences.
Person 1 - "Hey, look at that greb stain on the wall."
Person 2 - " go and lick it."
Person 1 - " fuck off, I am not a greebo."
Person 2 - " go and lick it."
Person 1 - " fuck off, I am not a greebo."