Skip to main content

I'll have your head 

A threat basically meaning that the recipient is in very serious trouble if certain conditions are met.
If I find out you're lying to me, then by God, I'll have your head!

have/put your head on the block 

to risk a bad thing that is happening to you by doing something or assisting someone

Please dear Van Abdullah I'm going to put my head on the block for you.

I hope Van's boyfriend is going to have his head on the block for her.

have you bumped your head? 

It essentially means you have you lost your mind? or it can be used to express your hatred or dislike for a particular activity or person, similar to kms.
"Moe's is better than Chipotle."
"Have you bumped your head?!?"
or

"This traffic makes me want to bump my head."

or
"Help! I have bumped my head and I can't get up!"