This postcard was a popular meme made by Douglas Gale of Ugly Baby. It says "The Earth is approximately 1 Giant Space Napkin from the Moon."
The back says, "The origins of Giant Space Napkins are still fiercely debated among napkin scientists."
Is it nonsense? Yah. Totes. Is it funny. Yah. Fer sure.
These postcards are sold in packs of ten.