2 Advil + 1 bottle of gatorade (or water) before passing out. force yourself to drink it all. If you can, eat something after you leave the bar.
... Most girls should start off with the morning after pill.. especially if they don't remember even a little bit of their last night..
Funny thing is when I was in Cancun in 05 I didn't have a hangover all week. I even got sick one night after excessive drinking but felt fine the next morning waking up at about 7AM???? It's weird what Cancun does to you it's like your need for sleep goes on vacation too. I would party till like 3-4AM and still be up before 8AM every morning. Though in normal settings I usually try to take a few advil with a glass of water before I hit the sack.