1 General Dodonna: The target area is only two metres wide. It’s a small thermal exhaust port, right below the main port.
2 Luke: Will a precise hit start a chain reaction that will destroy the station?
3 Luke: Is the port ray-shielded, so we have to use proton torpoedoes?
4 General Dodonna: No, that’s too hard. Your mission is to stuff a giant three-eyed Kinyenian potato into it.

Now, I thought up the idea of blowing up the Death Star by stuffing a potato into the thermal exhaust port, and then I immediately thought, "I'm sure someone else must have done this before. It's so obvious." I even thought I had vague memories of it being done in Spaceballs or one of those other really early Star Wars parodies that were all over the place in the late 70s and early 80s.

So I did an Internet search to find out exactly what other parody had already done this joke.

And I couldn't find any. Not only could I not find a specific example in an existing work, I also couldn't even find anyone mentioning this idea of stuffing a potato into the Death Star exhaust port. There are two possible explanations for this:

1. My searching was deficient and I missed all of the people who have in fact made this joke before.
2. Nobody has used this joke before.

2 just seems so implausible that I have to conclude that either 1 is in fact true, or alternatively that I just don't understand how anybody's minds work.

Oh, and to save you a different search.