English Idioms and Idiomatic Expressions 

Idioms: Anxiety and Fear - 2,
from: 'get the jitters'   to:  'at your wits end'

• get/have the jitters
  • If you get (or have) the jitters, especially before an important event, you become very nervous or anxious and begin to shake.
    "Some people get the jitters when they have to make a speech."
    
    
• have kittens
  • To say that you're going to have kittens is a dramatic way of expressing worry, anxiety or fear.
    "His mother nearly had kittens when Alex announced that we wanted to be a trapeze artist."
    
    
• jump out of your skin
  • If you jump out of your skin, you are extremely surprised or shocked.
    "Jane nearly jumped out of her skin when the horse put its head through the kitchen window!"
    
    
• get your knickers in a twist
  • If you get your knickers in a twist, you are anxious, nervous, or angry faced with a difficult situation.
    "Don't get your knickers in a twist! Everything is under control."
    
    
• nerves of steel
  • Someone who has nerves of steel is not afraid and stays calm in difficult or dangerous situations.
    "Fire-fighters need to have nerves of steel."
    
    
• on pins and needles
  • If you are on pins and needles, you are very anxious or nervous about what is going to happen.
    "Scott was on pins and needles while he waited for the result of the exam."
    
    
• quaking in one's boots
  • When someone is extremely scared, it is said that they arequaking in their boots.
    "When he saw the crocodiles in the water, he started quaking in his boots."
    
    
• scare (someone) out of their wits
  • If something scares you out of your wits, it makes you very frightened or worried.
    "The feeling that a house is haunted can scare people out of their wits."
    
    
• scare the daylights out of someone
  • If something scares the (living) daylights out of you, it terrifies you.
    "The sudden screaming scared the daylights out of me. I was absolutely terrified!"
    
    
• scared stiff
  • Someone who is scared stiff is so frightened that they are unable to move.
    "My mother is scared stiff of heights."
    
    
• shake like a leaf
  • If you shake like a leaf, you tremble with fear or nervousness.
    "At the beginning of the interview the candidate was shaking like a leaf."
    
    
• on tenterhooks
  • A person who is on tenterhooks is in a state of anxious suspense or excitement
    "The candidates were kept on tenterhooks for hours while the panel deliberated."
    
    
• tongue-tied
  • If you are tongue-tied,you have difficulty in expressing yourself because you are nervous or embarrassed.
    "At the start of the interview I was completely tongue-tied!"
    
    
• whistle in the dark
  • If you whistle in the dark, you try to hide your fear and pretend to be brave in a scary or dangerous situation.
    "Bob looks confident but he's just whistling in the dark; he knows he's going to lose his job."
    
    
• at your wits' end
  • If you are at your wits' end, you are so worried about something that you do not know what to do next.
    "When her son dropped out of school, Susan was at her wits' end."