Meaning:
If someone says they are going to play for keeps, that means they’re done playing around and they’re about to get serious.

The Origin Of ‘Playing For Keeps’
This phrase might come from the game of marbles. How so? In marbles, players draw a circle on the ground and then put some marbles inside. Afterwards, they take turns trying to knock the marbles out of the circle by flicking their own marbles at them. If they successfully knock a marble out, they might get to keep it if they win. I think at the beginning of a game, players can decide if they are “playing for keeps.”
Anyways, this expression with its figurative meaning has been around since at least 1842. It is written in the Hattiesburg American newspaper from that year:
“In the second and third heats, George realized this was a mistake, because it made Joe angry and he started playing for keeps.”
Example Sentence(s)
- Next time we play one on one soccer, I’ll be playing for keeps!
Similar Example:
- If I’m going to improve at the piano, I have to knuckle down and spend some time practicing every week.