U-Scan
A machine used to purchase goods with out directly going to a cashier. Often requires reading a screen to tell you what to do next, but no one ever reads anything and starts screaming at the U-scan attendant.

"Damn that cashier looks pissed and her line is way too long, lets go to U-Scan." 
Customer: "Excuse me it says please wait for the cashier"
U-Scan Attendant:"Yes sir you are the cashier this is U-scan, just hit the green enter button"
Customer:"No, it says im waiting for cashier"
U-Scan Attendant:"Yes and this is U-SCAN and you are the cashier, so just hit the enter button"
Customer:"So what do I do?"
Attendant bashes had off wall repetitively 