A work of satire.

I had an idea for a plot-based anime-esque comic that satirizes many issues within the modern world, and makes them very cartoonish. (An example would be the "Great wall of 'Merica", a giant wall created on the Mexican-American border with a laser on the top).
The problem is, I can't really think of a plot to go along with the premise. I don't want to write a very long comic (It should just be as long as an average British TV show), so an epic tale would be out of the question.

Any suggestions?

One-shot joke strips are a perfectly valid (and common) form of comicking. Especially for satirical comics. If you can't make a plot work, then let there be no plot.