A person who is the embodiment of garbage. One who posses the physical qualities of garbage. Not one in sanitation, but someone who is garbage. An adjective used as a noun.
Ben: Wow , Mike is being total garbage right now.
Ryan: Ya, he is a Gerund!!
The gerund is the verb form ending in -ing which acts as a noun. The one word riposte "Gerund" by some self-satisfyingly smug pedant indicates an abuse in its usage. It often muddies the intended meaning, and makes one want to lamp the complainant.
This usage fell into disuse in modern English and is now regional or dialectal. A similarity in usage can be noted in the European Portuguese language structure.