Our knowledge of these works is hampered somewhat by gaps in our understanding of the iconography. As we understand the work, the man is revealing a gateway to the Underworld - a passage to dark, carnal desires, through which she may travel to fufill her dreams, and perhaps pick up some groceries on the way back. What is unclear is the meaning of the pattens on the circular objects. Some suggest the patterns are not important at all - what matters is the way the discs are arrayed. It was the sign of 5 on a dice cube, suggesting that she is about to gamble with her soul when she enters the portal.

Or, it's just crap on the wall.