On the same vein, I find it to be aggravating to have a crowd of waiting customers and then when it is their turn they haven't even thought about what hey want. When the bar is full of thirsty patrons waiting for their turn to order and they have to wait for an indecisive person that would rather be texting instead of thinking about what they want.
I really enjoy the customers as a rule, but when I am "in the weeds" sometimes it is hard to be the cheery guy behind the bar and stay focused on the job of making the best cocktails possible with people trying to shout their orders or want to talk to me when I have 10 orders on the rail being constructed. Mistakes take time and any distractions from what I am doing will result in a longer time lapse before other customers will get their cocktails.
I guess that my pet peeves really relate the people with a strong "me" personality. I have many fabulous customers that all deserve and get the same quality service, impatience just slows the entire process and makes everyone in the bar uneasy.