Wild Nights at Whiskey Girl to be Had
Seriously. If you want a wild night, go here. Not only are you in the middle of the Gaslamp already, you may walk in and have your friends carry you out.
They have a long bar and food served late night status at the tables on the floor. They clear out a large section of the floor for dancing after ten or so. The DJs and music are pretty good normally, and the lighting and massive screens that you can watch from even the street keep up the party atmosphere.
Note however that there is a dress code after ten pm. It's pretty basic though, and as far as I know, it's just that you can't wear hats or bandanas in the evening.
Drinks are normally priced, but strong enough, and there is a good selection on tap, even for people who care about good beer. There is a photo booth in the back on the way to the restroom area which is perfect for catching your best drunk moments with friends. I know I have made some lasting impressions of ridiculousness via that booth.