get (one's) cards

To be fired from one's job. Primarily heard in UK. After messing up that account, I'm terrified that I'm going to get my cards from my boss. I heard Tommy got his cards for showing up to work late again. I want to stand up to the boss, but I'm afraid I'll get my cards, and I can't afford to have that happen.

get your cards

be dismissed from your employment. British informal

Cards are the national insurance card and other documents relating to an employee that are retained by the employer during the period that the employee works for them. Give someone their cards means ‘make someone redundant’.