get/have somebody by the short hairs

get (one) by the short hairs

To acquire complete control, dominance, or power over one, especially in a difficult or awkward situation. A reference to the hairs on the back of one's neck (not pubic hairs, despite popular misconceptions). By scoring a third goal in the last quarter, the home team really got their opponents by the short hairs. He found out about my involvement and is using it to blackmail me—he's got me by the short hairs now.
See also: by, get, hair, short
Farlex Dictionary of Idioms.

get/have somebody by the short ˈhairs

(also get/have somebody by the short and ˈcurlies) (informal) get/have somebody in a position where they must agree to what you want: We can’t go on strike because the boss will simply hire new staff. He’s got us by the short and curlies.
Short and curlies refers to the hairs on a person’s body.
See also: by, get, hair, have, short, somebody
Farlex Partner Idioms Dictionary
See also:
  • get (one) by the short hairs
  • have (someone) by the short hairs
  • by the short hairs
  • have someone by the short hairs
  • get (one) by the short and curlies
  • get someone by the short and curlies
  • have (one) by the short and curlies
  • have someone by the short and curlies
  • a tough spot
  • a tight corner