People
When I have a kid, I want to buy one of those strollers for twins. Then put the kid in and run around, looking frantic. When he gets older, I'd tell him he used to have a brother, but he didn't obey.
— Steven Wright

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker invents a dark prank around a double stroller with only one child in it. An empty seat first suggests a missing sibling, then becomes the basis for a threat about disobedience. The joke connects an absurd visual deception with a deliberately cruel imaginary family story.
Context reviewed