Look, if I said this to a neigbour's kid: "if you cross the fence into my garden, I'll slap your and take you to your parents", it would be a warning appropriate to the offence you want him to be scared of doing.
If you said "if you cross the fence and step on my carrots, I'll kill your father, rape your mother and sister and then burn them alive in your house, after which I will cut you open, disembowel you, cut off your head and put it on a stick to scare other kids", then you should be taken to a mental institution, no matter if you meant it or not.