When people order a beer at the bar, I generally ask them two questions:
"Would you like bottled or draft beer?"
"Import or domestic?"
For most beer drinkers, they already know what they want to drink. Ask them these two questions and you wont have to rattle off your entire beer inventory. But every now and then, there will be customers who aren't really sure what they want. Once you recite every single type of beer you have in stock, they will then ask you for a beer you didn't list. It happens all the time. Why? Why?
Why are some people so stupid?
My usual response to someone who orders a beer we don't have after I have listed off every single beer we have in the house:
"I didn't say we had blank beer".
I will then just stand in front of the customer and wait patiently for them to place their order. I secretly enjoy it when other customers overhear the conversation taking place with said clueless customers. When those customers nearby give me the "Are you kidding me? You have to deal with that crap?" look, I feel slightly validated. After the transaction, I happily I proceed to help the next person who actually knows what he/she wants to drink.