Just keep repeating "That's no moon" every time a new planet appears.
Animated Size Comparison Of Fictional Planets In Popular Culture

This is another size comparison video from MetaBallStudios (previously), this time comparing the size of various fictional planets found in popular culture from smallest to largest diameter. And also to things that actually exist in reality, like “New York City, Earth, the Earth’s moon, other planets in our solar system, and even to the sun itself.” I learned a lot by looking at it. Mostly, that– “Let me guess: if your penis were a planet, it would have appeared about three-quarters through the video.” That’s not what I was going to say. “Oh no?” I was going to say about halfway, just to be modest.