put/lay your head/neck on the block
put one's head on the block (for someone or something)
Fig. to take great risks for someone or something; to go to a lot of trouble or difficulty for someone or something; to attempt to gain favor for someone or something. I don't know why I should put my head on the block for Joan. What has she ever done for me? Sally tried to get me to put in a good word about her with the boss. But the last time I put my head on the block for anyone, it all backfired, and when the person goofed up, I looked like an idiot!
put your head on the blockor
put your neck on the block
If you put your head on the block or put your neck on the block, you risk your reputation or position by taking a particular course of action. When the Prime Minister called a by-election in his own constituency, he put his head on the block. He really put his neck on the block there and it's great to see his bravery being rewarded. Note: You can also say that you put your head on the chopping block. I'm not going to be the one who puts my head on the chopping block. Note: The `block' here is a special piece of wood on which a prisoner was made to place his or her head before being beheaded.
put your head (or neck) on the blockput your position or reputation at risk by proceeding with a particular course of action. informal
This phrase alludes to the block of wood on which a condemned person was formerly beheaded.