I'm not going to my close friend's 23rd birthday party
Why would you not go to your close's friend's 23rd birthday party?
No way, it's Friday and usually on a Friday I have hangovers
If he invited you I think you should go out of respect and principles especially if it is a close friend. Also, your excuse is terrible. You can just have the best of both worlds and have a hangover at your friends party!
He doesn't need me on his birthday.
I don't think you realize it, close friends just need their close friends to be at their birthday parties. Why not just skip the drinking the night before just this one week in honor of your friend? Good friends are not that easy to come by these days anymore.