Definition
To accept punishment or injury without retaliating.
Origins
From the Sermon on the Mount, where Jesus rejected the eye for an eye philosophy in favour of a more humble approach.
How People Actually Use It
A term used in an argument where the opposing side agrees to an insult or insults himself after a while in an effort to downplay the argument.
"Person 1: Shut the fuck up loser. I bet you’re so fat you can’t see your feet while looking down. Person 2: Yeah, that’s true lol Person 1: Yeah turn the other cheek, pussy."
Source: Urban Dictionary