Oh, man. ita, I'm so sorry.
My pet peeve is people not having their wallet out and ready when they get to the cashier. Dude, you were waiting in line to PAY--don't you think you could assume you would need to get at your money or credit card?
Here's my Rules of Bar Drinking - if you do not follow said rules, I give you the stinkeye (unless I'm bartending, and then I'll just internally sigh).
1. Know what you want before the bartender approaches you. If it's slow, and/or you have a couple questions about the menu or beers, no prob. But if it's packed and/or you have to ask your entire group if they all want Miller Lite, thereby wasting the bartender's time? No love for you.
2. Have your money out and ready to be presented before the bartender returns with the drinks. I'm not saying you need to know what your order is going to total, but have the money right there so you can quickly select the proper amount and give it to the bartender.
There's more, but those are the two biggest fouls I see.