Don't trust atoms. They make up everything!

Behind the Groan

Two Meanings Packed into “Make Up”

This joke turns on two ordinary meanings of “make up.” Someone who makes things up invents stories, so that person may be hard to trust. Atoms also make up matter in the literal sense that they are basic building blocks of the world around us. The setup gives atoms a human flaw, then the last four words switch back to science. It is short enough for a lunchbox note and familiar enough for a classroom without requiring a chemistry lesson first.