For the uninitiated, that's "Rolling on the floor laughing my ass off."
Which is what happened to me when I read to the end of this article about the handover of Abu Ghraib prison to the Iraqis. At the beginning, I thought, "What bunch of lackeys the Iraqis are--spewing the US party line about how the American abuses have been brought to light through an investigative media." But then I learned what I already knew. The empty structure represented an empty gesture.