Diddly squat informal pronoun
This expression means anything.
I know diddly-squat about her family.
Jane didn't care diddly-squat about what his parents said.
This phrase is a derisive answer to an inappropriate, unreasonable, or stupid question
Whatever you mention, someone will get it.
To do domething based on your emotions rather than for rational reasons
I can't believe that Tom beat his classmate. He's always the one who let his heart rule his head.