Our News Junkie noted the other day that ACORN and the Dems are playing for keeps. That is opposed to "playing for clearsies," which is the gentlemanly, softball, McCain approach.
Games with acorns and other nuts or rounded stones go back to the beginning of human time but, when I was a lad, marbles weren't a popular game. Games with marbles remain very popular in the Third World.
Here are a few expressions from marbles:
Playing for keeps
Knuckle down
Lost his marbles
Pick up one's marbles
Over the line
I'm sure there are plenty of others. Help me out if you can, in Comments. I love the etymological and cultural derivations of expressions. Don't you?