In most comedies, at least some of the humour comes from embarrassing stupid people. Sometimes, MOST of the movie's laughs come at the expense of characters that can be charitably called dim. The reason My Cousin Vinny is my eighth-most favourite movie of all time, is the almost complete dearth of stupid characters in the 1992 breakout movie for Marisa Tomei.
If you haven't watched the movie in some time, do yourself a favour and watch it again. Nobody's stupid, except for possibly the bar rats that Joe Pesci's title character takes in a bet. Otherwise, they are all good people, trying to do the right thing. And the clash between Pesci's Jersey lawyer and the residents of the small Alabama town he comes to, to defend his cousin on a robbery/murder charge, is where the laughs are.
Ralph Macchio plays the throwaway role as Bill Gambini. He calls in his cousin Vinny, who comes to town for his first big case as a newly-minted lawyer. He's accompanied by his girlfriend, Mona Lisa Vito. Tomei turned Vito into an icon, displaying brains beneath the Jersey princess persona, and saving things at the end. In the meantime, she gave voice to millions by stamping her foot and saying "My biological clock is ticking like this." And people haven't stopped referring to biological clocks since then. Tomei might have been a surprise choice to some in winning her Oscar for the role. But not to me.
The judge, the wonderfully laconic Fred Gwynn, was on to Vinny right from the start, but was slow getting his proof of some Yankee shenanigans (Vinny was name-dropping another lawyer's name to get the right to defend Billy). But he wasn't stupid. And certainly, the sheriff played by Bruce McGill and the DA played by Lane Smith weren't stupid, despite believing in their own open-and-shut case against Billy and his friend.
It's always a mistake to equate stupidity with lack of experience. Vinny was completely clueless about the law because he got a night-school diploma and didn't understand Southern hospitality. But he learnt quickly enough and rediscovered the treasure he had at his side just in time to come away a winner.
But the real winner is the viewer at home, watching a smart comedy without any stupid people to spoil the good time.