on the block

1. put or go on the block . Offer for sale, as in These paintings will all be put on the block . This usage alludes to the auction block, the platform from which the auctioneer sells, so called since the mid-1800s.

2. put one's head on the block . Take a great risk, make oneself vulnerable, as in I'm not going to put my head on the block just to save her reputation . This usage alludes to the executioner's block, on which victims are beheaded, so called since the mid-1500s.