When one fails to remove a stem from one's marijuana crop before inserting in to a blunt, it can often cause a hole in the blunt. In order to reduce the loss of perfectly good marijuana smoke, one may use a blunt bandage, which is a little piece of a blunt laid over the hole in the aforementioned blunt. This acts as a patch for the blunt, and thus, as a barrier for the intoxicating fumes that may send you off to fun land for a time.
"Awe man, I missed a stem. Break me off a blunt bandage."