What does "spill the beans" mean — and why is it funny?

informal

Meaning

To reveal a secret, often by accident.

Where it comes from

One theory traces it to ancient voting with beans, where knocking over the jar exposed the result early; the phrase took its modern sense in early 1900s America.

Why it is funny

It turns telling a secret into a clumsy kitchen accident. You picture beans clattering everywhere, impossible to scoop back up — which is exactly what a leaked secret is like. The humor is the mismatch between a small physical spill and a serious social slip.

Used in a sentence

"Don't spill the beans about the surprise party."