These informal idioms can be used either about yourself or about a third person. l'm fed up (to the back teeth) with trying to live on such a small wage. I'm at my wits' end trying to keep things in order. (wits intelligence, brains) I've had it up to here with this organisation! These informal idioms are generally used about other people. Your boss will have/throw a fit when he finds out you forgot to reply to those letters. (You can also say go off the deep end go spare do his nut blow a fuse.) These less informal idioms describe other people's anger and are based on the word blood If someone's blood is up, they are very angry or excited and may react in a violent way. If you are after someone's blood, you want to catch them in order to hurt or punish them. If you are out for blood, you are determined to find someone to attack or blame for something bad that has happened.