Putting up a K. AKA putting up 1000 dollars in the bank.
A K means Kilo which means 1000. "Kilometer, Kilobyte"

In baseball when a person is struck out, the pitcher will receive a 'K' in the score books. They will also put up the letter 'K' on a sign usually in the outfield.

If you strike out your bank account you have put up a K which means putting 1000 dollars in your account.