My wife got the biggest laugh out of these. Found on Information Aesthetics, these double bed sheets are printed with a ruler starting at the center and measuring outward. You can always tell whose side you're on because the ruler is printed to be read when you are in the bed.

The sheets are from DesignWise, a store chain with designer products in Portugal, Spain and France. DESIGNWISE is a brand that edits original products and objects created by Portuguese designers.