give (one) the boot

1. To fire one. After messing up that account, I'm terrified that my boss is going to give me the boot. Are you seriously going to give me the boot after five loyal years on the job? Management promptly gave the new accountant the bag after his miscalculation cost the company hundreds of thousands of dollars.

2. To end a relationship with a romantic partner; to break up with one. No, Susan is single again—she gave Kelly the boot. I loved Mary so much and thought she loved me—I never expected her to give me the boot and then move halfway across the country! A: "Did you hear that Liz gave Dan the boot?" B: "Wow, I never thought those two would break up."