"Robo is slang for Robitussin, which some people drink to get high." - Craig Finn[1]. It's also a short form of the name "Robbie Robertson."

The lines "blew red...into a tissue" and "over the counter" also likely reference the recreational use of Robitussin.

May also refer to the drummer from Black Flag and The Misfits, ROBO.

from The Swish