(one's) ass is grass slang rude
One is going to be killed.
His ass is grass because he's the only witness.
Someone is going to be beaten.
Don't let me see you one more time, or else your ass is grass.
Someone is going to receive heavy punishment, especially by being dismissed, expelled, grounded, and so on.
"She's missed the deadline for the third time" - "Her ass is grass".
If John's dad knows that he played truant, his ass is grass!
To punish someone or something harshly
Beat someone up
Someone is going to receive a harsh punishment for what he or she has done something wrong.
Small-time criminals will face the full consequences of the law while those who commit large-scale crimes will go unpunished.
“Your ass is grass” originates from the fact that when someone dies their body decomposes to become fertilizer for grass, hence someone’s ass being grass. The origin of “Your ass is grass” is the shorthand of the expression “Your ass is grass and I’m the lawnmower”. The full statement when said to a person means that the individual making the statement believes that they have complete domination or control over the person the expression is directed to.
Used to to emphasize that attention is paid to the individuals who complain or cause problems
Sometimes, you shouldn't be so quiet because the squeaky wheel gets the grease.