the punishment fits the crime

The punishment given is equal to the offense done. A: "Mom! I only snuck out a couple of times." B: "Yes, completely betraying our trust! You're grounded for three months, with no car or phone privileges—I think the punishment fits the crime." If you stop being friends with Tiff because she started that nasty rumor about you, I'd say the punishment definitely fits the crime. I mean, how can you trust her ever again?