Put/lay your head/neck on the block
Definition 1 of 2
Pro Tip 1/3Risk Connotation
The phrase suggests a high risk with potentially serious consequences. 
She knew that whistleblowing could mean losing her job, but she put her head on the block anyway.
Pro Tip 2/3Business Ventures
Often used when someone is taking a big financial or career risk. 
He put his head on the block by funding the innovative but uncertain tech startup.
Pro Tip 3/3Seriousness
It's used in contexts where the risk is not trivial but has significant impact. 
In vouching for her controversial plan, I am effectively putting my head on the block.