big one

1 informal :  a thousand dollars The house in the background, we bought it for 70 grand in 1967, it would go for two hundred big ones now, easy … — John Updike

2 informal :  an extravagant lie :  whopper Talking about lying, I thought, I had just told a big one. — Elizabeth Chandler

3the big one or less commonly the Big One :  an extremely large and destructive earthquake … the prediction that the Big One may come in December is triggering tremors up and down the Mississippi Valley. — Michael J. McCarthy