...and I am still no taller

Had a lovely weekend of eating and drinking some nice wine. I was wide awake at 1am and raring to continue partying. Unfortunately all my friends were yawning and stretching by then, so we headed off home. Probably for the best - at least I was hangover free the next day - woohoo!!
How is it that you can have a few drinks one night and have the biggest hangover in the world, then another time you can drink a bottle or two of wine and feel fantastic the next day!?