Well since you put it that way:

There's already an scale that prints UPCs in the produce department for customers to use. I'll just put the package of steak on there, punch in 4011, and scan out my "bananas" at the self-checkout. ;)

(But they'll still know who I am. Walking out is cleaner, and has fewer steps.)

The man in the sky can see what is being scanned in real time, it’s on his video display just like the cash register except overlayed on the video of you. If they see a ribeye in your hand and it says bananas on the screen, good chance they’re going to stop you before you exit (assuming they can mobilize to do so).

Honestly if you’re a thief this is just a dumb idea. Probably works for the original commenter a few times fine. But it’s way too obviously and intentionally theft. You need to come up with something you can claim was an honest mistake.

Find another item that sounds similar but is cheaper and use that upc. If you’re keying in the upc, on a scale or something, then find one that’s cheaper but off my 1 digit or something where you can say it was a typo and you didn’t notice. Those kinds of things are more defensible. None of us have been trained to be a cashier so honest mistakes are a strong defense to any claim of misconduct.