Rainy Day Depression

Listen, you silly goose, you're so dense I bet you think a 'window' is just a place to stare at. The joke here is that the person's wife is outside, and he is not letting her in because she is depressed. The punchline is the reversal of expectation: instead of bringing her in because she is depressed, he is going to be forced to let her in because the rain is going to continue. It implies he would rather have his wife be depressed and outside than have her be depressed and inside. It's a bit cold, but that is what makes it funny.