Three sheets to the wind

A slang phrase that means one is inebriated. Sometimes the number of sheets can vary depending on the drunkenness, but I typically say three.

Example usage: Did you see Greg last night? He was three sheets to the wind.

To elaborate: This derives from sailing. If I had to guess, I would say that two of the sheets (or lines) in question are the port and starboard jib sheets (the jib is a smaller sail that is positioned over the bow). The third would then belong to the mainsail. This accounts for all of the crucial lines in your typical small to mid-sized craft. The point being that, if all three are flapping loose in the breeze, or "to the wind", then you have about as much control as a well-embalmed bar patron.