Irritation from the alcohol, most likely. With time (and as you age), your lips tend to lose the moisture that prevents them from chapping and burning, which is then intensified by alcohol. Lip balm will help ... and perhaps a daily intake of Riboflavin (Vitamin B2), as the deficiency of Vitamin B2 can lead to inflammation, lesions, and sores around the mouth.
lol I've never had one of those yet... my friends always make me drink a crap lode of water. I'd say it has to do with the blood flow or something... I am most likely wrong
Haha wow... Meaning? You're gonna have to spell this one out 4 me I'm pretty dense remmember?=P
Maybe it's from what you were doing the night before ;P