Never been treated so poorly by a waitress. This actually happened:
She asked me and my friends for ID (we are all 23-26) before serving us. When we took a minute to think about which drink we wanted she said "wow you guys are really bad at this". She continued to be insanely rude to us the entire time she was serving us from behind the bar for absolutely NO REASON.
While we were drinking she went off duty and started flirting with a guy sitting next to us at the bar. As we were leaving she said loudly to him "23 year olds are so f***ing stupid!", looking right at us. She then laughed loudly and said "Oops!" as if she hadn't intentionally insulted us in some pathetic attempt to impress this guy who seemed to have no interest in her. It was all the most bizarre experience my friends and I have ever had.