He who excuses himself, accuses himself

he who excuses himself, accuses himself.

I want to know the meaning of this phrase.

It's an answer to the question "Who farted?"

It's a translation of the rather snappier French proverb "Qui s'excuse s'accuse". RRC was joking, smruti: it means "if you feel you have to produce excuses and justifications for something you've done, that shows you really know you're in the wrong".