I asked my science teacher if atoms can be trusted.

This joke hinges entirely on a delightful bit of wordplay, specifically a pun. The humor comes from the double meaning of the phrase "make up everything." In a scientific context, atoms literally "make up everything" because they are the fundamental building blocks of all matter in the universe. From the air we breathe to the stars in the sky, it's all composed of atoms.

However, the punchline cleverly twists this scientific fact into a social commentary. When someone "makes up everything" in common conversation, it means they are fabricating stories, being dishonest, or simply not telling the truth. This implication of untrustworthiness is what gives the joke its comedic kick, playing on our everyday understanding of deception.

So, while atoms are indeed the honest-to-goodness foundation (Review) of reality, the joke uses a linguistic trick to playfully suggest they're a bunch of fibbers. It’s a perfect example of how a simple phrase can bridge the gap between scientific fact and everyday human foibles for a quick laugh.