(On our self serve copiers, the customer must press a button on the screen indicating whether or not they’re finished copying. If they press “YES” they receive a receipt to take to the cashier.)

Customer: “I’ve never used these before!”

Me: “Not to worry, it’s really easy.”

(I proceed to give her the run down, including telling her not to press the “YES” button until she’s done with all of her copying for this visit. The customer proceeds to make one copy and press “YES”.)

Customer: “What? I don’t want a receipt yet!”

Me: “Well, ma’am, you just told it you were done making copies. Next time, press the ‘NO’ button if you still have more to make.”

(The customer proceeds to make another copy and presses “YES”.)

Customer: “Stupid machines!”

Me: “Ma’am, if you aren’t done, you should press ‘NO’.”

Customer: “I know! I know! I know! I know what I’m doing! I’ve just never used this machine before!”

(I finally gave up trying and went back to my work. She eventually came up to my register with over a dozen copy receipts, complaining how stupid the machines were.)

Related:
Stupidity Is The Mother Of Repetition, Part 3
Stupidity Is The Mother Of Repetition, Part 2
Stupidity Is The Mother Of Repetition