Being drunk sucks. You feel sloppy. You make a fool out of yourself, and I've learned that first impressions can cause people to label you as a drunk or an asshole forever, regardless of how you are when you aren't drinking. I only used to drink on weekends, but when I did I made a dickhead out of myself. Learned the hard way that even if you try hard to be nice to someone or show that you aren't a drunk, if first time you met them you made a douchebag out of yourself, that's pretty much the impression of you that they will have from that point on.
I also hate that feeling the next day. When you wake up with a headache, stomach ache, dry mouth, and dread looking at your cell phone to see who your drunk dialed or texted.