1. I once watched two yahoos drink that much each on a 8AM flight from LIT-DFW (

).
2.
See this thread.
3. On a more serious note, I have seen a few pax cut off, and in one case, I got a guy cut off before departure (he was WAY beyond hammered, and I had personally witnessed him chug no fewer than 8 Bloody Marys in the lounge before departure...he ended up being seated next to me on a transcon). The F/As managed to find me the one other seat available on this full flight, and the guy passed out right after takeoff...the purser was quite grateful for the heads up on the guy's condition. IMHO he shouldn't have been allowed to fly, but who am I to say.)
4. I was "cut off" once on Continental Express as they have a limit of 4 drinks per pax (two double scotches during a 3+ hour ERJ flight doesn't strike me as excessive, but I guess their limit is reasonable).