courtesy of a site called the sex dictionary...
glory hole - n.
A hole cut through a wall, allowing anonymous sex between people on either side of the wall. Often found in gay sex clubs.
A glory hole is a small fist-sized hole between private video booths in an adult bookstore. The hole is placed about hip high for the average guy and is large enough to place a man's penis through to let the person on the other side perform whatever sexual activity he pleases on it.