Cars have windows. Houses have windows. So it can't be windows that makes the car go.
I swear I don't understand, and he tried to explain it to me. He said it's a double meaning with Windows the operating system but I just don't don't don't get it.
Can anyone make this understandable to me? I may have screwed up the retelling, because honestly I have no idea what the hell's going on with this joke.
The humor comes from the unexpected final line. It's what's sometimes called an anti-joke, where instead of a punchline the final line is so banal as to be ridiculous, and that unexpected banality is the source of the humor.
I love anti-jokes, but it's hard to enjoy them if you're expecting an anti-joke, which makes looking up anti-jokes really unsatisfying.