A work of art, symbol, or sketch hidden behind a frame, mirror, headboard or other wall attachment of a hotel or motel room. The term is attributed to Joshua Homme, who created many wall tattoos while touring with Queens of the Stone Age. Some might try to link this practice with "anarchy" or "fighting the man" but these attempts usually end in fail. How serious can your statement be taken if you hide it under a $5 print?
"This hotel room smells like a band was in here! Quick, look behind the mirrors for Secret Wall Tattoos!"
Dude 1: Whoa, why are you taking down that picture frame?
Dude 2: I'm going to make a secret wall tattoo! I'm totally going to defy authority and feel like a rebel!
Chick 1: I'm never sleeping with either of you.
Chick 2: Me neither.