be out for blood

be out for blood

To seek vengeance in an especially hostile or belligerent manner. This phrase is often used hyperbolically, although it can refer to physical violence. I'd avoid the boss if I were you—he's out for blood and screaming at everyone he sees. Some neighborhood kids beat me up last night, and now my brother is out for blood.
See also: blood, out

be out for blood

if you are out for blood, you are determined to find someone to attack or blame for something These people are out for blood and if they find out you're involved you're in serious trouble.
See also: blood, out