"Schmuck" is probably the first Yiddish word I ever learned, as it was (and may still be) my father's favorite. And, oh, what a great, noxious, churlish, pistol-crack of a word this is, with its slurry start and hard-consonant finish. If it wasn't a curse word, you would think it was a curse word.
It is a curse word, though, and don't let anyone tell you otherwise. There are some that will argue that this is an adaptation of an identical-sounding German word that means "jewelry," but the most convincing etymology of the word is the following: it comes from baby talk. This theory was proffered by author Michael Wex in his book "How to Be a Mentsh (And Not a Shmuck)" and is as follows:
"Schmuck" started with "shteck", which means "stick" in Yiddish. When parents would refer to their baby's penis, they would call it a "shteckl," because you can make anything small and adorable in Yiddish by adding an "l" sound to the end. This then became "shmeckl," which, indeed, is another Yiddish word for penis. And, finally, when the word was no longer cute, the "l" dropped off the end and it because "schmuck."
Schmuck is still used to mean penis, sometimes. But mostly it means ... well, a few things, none of them good. Here's a joke:
What's the difference between circumcision and divorce? With divorce, you lose the whole schmuck.
So, you see, it means penis, but also means someone you find contemptible.
Depending on context, "schmuck" can mean "idiot," or it can mean "jerk," or it can mean "loser." It's a plastic term, less one with a set definition than a word that acts as a mantle to wrap your contempt in. The guy who accidentally started a fire? What a schmuck! The guy he set on fire? Poor schmuck! And you, watching the whole thing and not helping? Do something, schmuck!
Here are some quotes that demonstrate the proper usage of the word schmuck:
From Humour and Religion: Challenges and Ambiguities, Hans Geybels, Walter Van Herck: "An Orthodox Jew is walking down the street in a definitely non-Jewish neighborhood, when he hears someone talking in Yiddish. He turns back and finds an animal store, where he finds indeed a parrot that speaks Yiddish perfectly. 'This,' the owner tells him, 'is a real Jewish parrot. It can recite psalms in Hebrew as well.' The man buys the animal, puts a tiny kippa on its head and throws a little prayer shawl over its wings. In the synagogue the next Sabbath he bets with each of the men for twenty dollars that the bird will speak Yiddish and sing a psalm. But the parrot stubbornly refuses to open its beak. The man is furious and goes home with the bird on his shoulder. Suddenly the parrot starts laughing: 'You schmuck, next week we'll return to the synagogue and bet for a hundred dollars each. And then I'll talk!'"
From The Ultimate Book of Jewish Jokes, David Minkoff: "Sadie tells Maurice, 'You’re a schmuck! You always were a schmuck and you always will be a schmuck! You look, act and dress like a schmuck! You’ll be a schmuck until the day you die! And if they ran a world-wide competition for schmucks, you would be the world’s second biggest schmuck!' 'Why only second place?' Maurice asks. 'Because you’re a schmuck!' Sadie screams."
The New Yorker, Volume 77, Issues 10-16: “A schmuck is someone who does something that you don't agree with. ... The Eskimos have four hundred words for snow, and the Jews have four hundred words for schmuck."
Thirty-Nine Years of Short-Term Memory Loss, Tom Davis: "We had submitted that script to SNL with 'schmuck' as Lincoln's word choice. But there was an objection even to 'schmuck,' which, our censor at the time, Bill Clotworthy, said was a Yiddish word for 'penis.' Al [Franken] recalled to him the Lenny Bruce explanation, 'Like a schmuck I drove all the way to Brooklyn,' which, Al pointed out, did not mean 'Like a penis I drove all the way to Brooklyn." Lorne [Michaels], who didn't feel like going to the wall for this one, sent Al a memo: 'You can't say 'schmuck,' schmuck."