So, I just recently started watching a show called Three Sheets on the Mojo channel. The show is all about drinking excessively in a bunch of different countries. It's on its third season already, and I find it highly entertaining.
Before watching this show, I had never even heard of the expression three sheets to the wind. This was a shocker to some, and I guess it's quite a common expression. Somehow it slipped through the cracks. It basically means being totally drunk and wasted. Not sure where I would have heard it... I know for sure that no one I know has used the expression to describe excessive drunkenness.
Anyway, in case anyone wanted to know about its origin, I did some investigating. It's a nautical thing. Sheets are ropes that hold sails in place. When you have three sheets blowing in the wind, the sails will flap around and cause the boat to get really wobbly much like a drunk person. From what I read, sailors used to rate the level of drunkenness using the sheets scale... from one sheet (tipsy) to three sheets (fall over drunk).