A "Karen" has gone viral after she allegedly got into a physical altercation at a Woolworths after trying to steal Ooshies from an old man's trolley.

The details of the fight were posted on Reddit by a shopper who witnessed the incident.

“So this literally just happened about half an hour ago and it p*ssed me off,” the shopper wrote on Tuesday.

“I finish up my shopping and the total came to $60, so I went collected the 3 Ooshies,” the shopper wrote, saying they first offered them to an elderly woman who “respectfully declined”.

“I then see an older gentleman and ask again. He said yes and that they would love them as his oldest [grandchild] is only 7.”

“Perfect, so I hand them over (to the elderly man) and that’s when I hear a troll clearing her throat. I turn around to see a ‘Karen’ staring at me standing next to her son as he just looked at his phone. I wasn’t in the way of anything so I just gave her a confused look.”

The shopper explained that the "Karen" then argued with them about the Ooshies.

“What about my son,” the "Karen" said adding, “If you‘re giving them away you should give some to him.”

The shopper said that 14 was a "little old" and that they wanted to give the Ooshies to someone with younger kids.

The "Karen" suggested a trade of the unopened Ooshies for some of her son's duplicates.

“Thank you but I’d rather the kids open them as that’s half the fun,” the elderly man said.

She then offered six Ooshies to the shopper for their unopened three, opening up her bag showing she has a swag of the collectibles.

“Sorry these are for my grandkids,” the elderly man said.

“Just give me the damn things,” the woman allegedly said.

According to the account on Reddit, things got physical.

“She then lunges forward and snatches them out of his cart, I see this coming so I grab her around the wrist stopping her from taking them,” the shopper wrote. “People started watching the incident.”

“Let go or I’ll have you arrested for assault,” she is reported to have said.

“Only after you let go,” the shopper said.

A store manger then had to intervene between the group, and the woman walked off.

“The manager apologised to the old man and he even cracked a joke about how he hasn‘t had something stolen off him since the white man came to Australia (he was Aboriginal) and thanked me.”

Others were quick to comment, saying that they've seen similar issues play out when small items are given away.

“I remember the beanie-baby craze and when McDonalds was giving away mini-beanie-babies with their happy meals and people were crazy about those things (my mother collected them). They were SO expensive too! I bet she was going to re-sell no doubt,” one user commented.

“I worked there during the first teeny weeny Beanie Bratz craze,” another said. “We had a limit of 2 that you could buy without a happy meal purchase, and only were giving out one version at a time until those boxes were gone, then moved on to the next."