The type of person who (for lack of brains, consideration or any other reason) cannot use an ATM in a timely manner.
Common behavior includes re-reading the screen several times, making incorrect selections despite the thorough reading process, and at the end of the transaction scrutinizing their receipt (before standing aside) like what just transpired was a miracle...all while oblivious to the growing line.
Extreme cases involve the mom who thinks it’s cute to have her 3 year old press the buttons, the business owner who thinks its ok to scan 72 checks in a row, and elderly person who forgot their glasses and "don't know how these machines work anyway".
Boss: Hey, haven't you been at lunch for over 2 hours now?
Employee: Yeah, but I was stuck behind an ATMoron. He was just trying to withdraw $20 and it took an hour.