Better a fool at a feast than a wise man at a fray.
Ivanhoe by Sir Walter Scott
Wamba the Fool is pretty much my favourite character in Ivanhoe. He just gets to put everyone else and their idiocy on blast with complete immunity himself. And, as evident in the quote above, he’s full of cogent axioms and quotes. He also apparently has a healthy sense of self-preservation, unlike most of the rest of the jokers in the story. I particularly loved the interpretation of him in the 1997 miniseries.

Fictional fools often have a biting wit that satirizes the follies of their masters, but they get away with it because they’re only an “addlebrained” fool and they’re providing entertainment in the form of wordplay and witticism. In this capacity, they often display a knack for seeing past the societal niceties and provide an insight into people’s true hearts and minds.
Fools themselves often act and are treated as outside accepted societal conventions, (unless of course you count the status of “fool” as being its own convention, which it sort of was) exempt from the same scrutiny and standards as others because they have already been declared “fool” and no further thought is wasted on them.

Though there isn’t an equivalent role I can think of in our society today, unless it be social media users, there’s nothing really stopping any of us from taking up the fool’s mantle and getting in some good zingers without fearing the repercussions.