Oh they can do so much worse than that. Wait until the total is rung up and then begin the search for a check book, careful fill out the check asking for the correct amount at least 3 times. Then before tendering the check carry out all the bookkeeping on the stub. Tender check - ID - return to bottomless purse for wallet - find ID. All tasks complete, a light conversation with the checker about the trivia of the day.
Of course 10 of the 200 items have no bar code so it has to be called in, looked up, and reported back. This is all enhanced by the first day on the job checker. And, you have to pee like a sick mule.
Now why would you say that after reading that it's my pet peeve?:D
You don't need Dr. Wrong in order to learn to communicate. Patterns for clear communication are learned socially. Everyone learns to code switch, depending on the social group they're communicating with. Slang, short hand, invented words, and all of those things that drive prescriptivists up the wall can be more effective depending on the social setting. Many of these features can indicate group identity--- a part of the message that would be lost by exclusive use of grammar book English.
That's a Caribbean sourced modification which comes from the mixing of the Hindi language (from the cheap labour workers brought to the islands to manage the black slaves) and the English language that most islands are at now.
So it may be perceived as a 'ghetto black' sound in North America, but it's actually VERY common in the islands.