As of 2010/2011, this term is the subject of legal action (and considerable discussion) in Baltimore, Maryland, USA, where a cafe owner has trademarked the term. See e.g. The Baltimore Sun's article "Catonsville man challenges Hon trademark".
Definitions include: An unlicensed bar or nite club usually open well after legal closing hours. Seems to be of Southern US origin, I have heard its use in Detroit, Chicago, and Milwaukee. After the show, we went to that blind pig on 26th St and stayed until dawn.