Fooey! The porchlight is burnt out, and I can't see whether it's dark outside or not.

The line plays as a comic complaint built on a small domestic inconvenience (a burnt-out porch light) that escalates into an absurd epistemological problem: without the artificial light, the speaker claims they cannot even tell whether it is dark. The humor comes from reversing what we normally assume—darkness is what makes us turn on a light—so the failed light becomes the supposed cause of not knowing the state of the world. It can also be read as a wry comment on dependence on external aids (technology, routines) to interpret reality, and how their absence can make even obvious things feel uncertain.