Unexpected Introduction

I brought my girlfriend home and introduced her to my family. My kids liked her, but my wife seemed upset.

Explanation

Experiment

The humor is in the unexpected reaction of the wife. The narrator introduces his 'girlfriend' to his family, which includes his wife. The audience would expect the wife to be upset, but the setup makes it sound like an introduction of a new person in a non-problematic situation. This creates a funny misunderstanding.