"I'll never speak to you again as long as I live," said Joe, rising. "There now!" And he moved moodily away and began to dress himself.
"Who cares!" said Tom. "Nobody wants you to. Go 'long home and get laughed at. Oh, you're a nice pirate. Huck and me ain't crybabies. We'll stay, won't we, Huck? Let him go if he wants to. I reckon we can get along without him, per'aps."

"But it's ever so much longer, and we're so late," grumbled Duncan.
"Who cares?" cried Elsie, stolidly. "I'm a girl and I'm not going to climb up the hill in this heat."
Duncan stared again. He had never heard Elsie complain of the hill before. Usually they scampered up it, and rolled down the steepest side—not, truly, when there was milk to carry, but at other times. And now Elsie was walking along in a languid, mincing fashion, as if she had no more fun in her than Robbie himself, and had never scampered bare-foot over the moor six days out of every week, no matter what the weather might be.
"There's Robbie at the garden gate beckoning us. I expect mother's very angry," cried Duncan, despairingly.
"Who cares? let him beckon," Elsie replied, with the most provoking indifference. "Run on by yourself if you're afraid."

c.1888, George Manville Fenn, Dick o' the Fens: A Tale of the Great Eastern Swamp,
"No, but it's not nice all the same to live in a place where lots of people were murdered."
"Tchah! who cares! I don't. It's a capital old place, and you never dig anywhere without finding something."
"Yes," said Tom solemnly, "something that isn't always nice."

"Well," said Peter Piper, "we have been called Meg and Peg and Kilmanskeg and Gustibus and Peter Piper instead of our grand names, and now we live in a place called Racketty-Packetty House. Who cares! Let's join hands and have a dance."

It makes no difference if you fall on the whirl. Who cares? And when you are through dancing you can go out to the faucet and get yourself a drink—provided the water hasn't been turned off.

Freddy Farmer added two one-dollar bills to the hockey tickets and walked away. The two soldiers gaped down at the two tickets and the two dollars.
"What's the matter with that guy; is he touched?" one of them mumbled. "And did you hear him, Fuzzy? He didn't even speak English!"
"Who cares?" Fuzzy asked as he came out of his trance. "Two four-buck-forty hockey tickets, and two bucks in cash! Who cares if the guy is touched? He's okay by me!"

Who cares

Meaning

Phrase