These 10 mob movie slang terms will be familiar only to true fans of gangster movies.
What Does 'The Vig' Mean in Mob Movies?

If you know about the vig, congratulations: You've probably paid close attention during The Irishman or Be Cool.
Hint: It doesn't stand for vigorously, which is how mob guys beat up people who are short of it.
The Vig Meaning

"Vig" is short for vigorish, aka juice. If you take out a loan from a loan shark, expect to pay interest, and probably a lot of it. This interest is called "the vig."
As Frank Sheeran explains in the book I Heard You Paint Houses, the source material for The Irishman, a waitress at a diner might borrow $100, and agree to pay back $12 a week for ten weeks.
"If she couldn't afford the $12 one week she'd just pay $2, but she'd still owe the $12 for that week and it would get added on at the end. If it wasn't paid on time the debt would keep piling up," Sheeran says.
What Does It Mean to Go to School in a Gangster Movie?

Going to school is a thing Henry Hill refuses to do early in Goodfellas, but does in a different way later in the movie.
Hint: In mob talk, "going to school" doesn't mean leaving a life of crime behind to get your bachelor's degree and become some kind of regular schnook.
Not usually, anyway.
What Going to School or Going to College Means in a Gangster Movie

Both are synonymous with "went to prison." I Heard You Paint Houses can be a little confusing because sometimes Frank Sheeran is talking about going to school, and sometimes he's talking about going to school.
He mentions that one character "went to school in 1967," and a paragraph later says another character "came out of college and went straight to work for the union." Does he mean college, or college? It isn't clear.
Of course, as Henry and his friends learn when they cook sumptuous prison meals in Goodfellas (above), going to school doesn't have to be so bad.
What Is 'Candy' in a Mob Movie?

Sounds like something you get for your gumar on Valentine's Day, right?
Hint: No — not unless she's thinking of talking to the feds.
'Candy' Meaning

As we learned in The Irishman, "candy" refers to explosives.
You wouldn't send someone a candygram unless you wanted to send them a very, very nasty message.
What Is a Gumar in a Mob Movie?

It's not the prettiest word, is it? If someone calls you one, you might even be offended.
What a Gumar Is

The word isn't pretty, but a gumar usually is: The word refers to the girlfriend of a married gangster, like Janice Rossi (Gina Mastrogiacomo), the girlfriend of Henry Hill (Ray Liotta) in Goodfellas.
Later, Henry starts dating Janice's friend Sandy (Debi Mazar.)
What Is a Fugazi in a Gangster Movie?

No, it does not refer to the Washington, D.C. post-hardcore band Fugazi, led by Ian MacKaye.
What Is a Fugazi Is

As Joseph D. Pistone, aka Donnie Brasco, tells Lefty Ruggiero (Al Pacino) early in Donnie Brasco, a "fugazi" is a fake. When Left tries to sell him a ring, Brasco passes on it immediately, telling him he should give it to a wife or girlfriend who doesn't know the difference between the real thing and a fugazi.
What Does 'Sleep With the Fishes' Mean in Mob Movies?

This is an easy one.
In The Godfather, Sonny Corleone (James Caan) receives a "package" while waiting to hear about the status of Luca Brasi, Vito Corleone's enforcer. It turns out to be a "Sicilian message" that "Luca Brasi sleeps with the fishes" But what does that mean?
Sleeps With the Fishes Meaning

No, it doesn't mean Luca has a mermaid as a gumar.
It means he's dead.
What Does 'What It Is' Mean in a Gangster Movie?

In a Blaxploitation movie, "what it is," might just mean, "What's up?" But it means something different in a mob movie like The Irishman.
What What It Is Means in a Mob Movie

In Irishman-speak, "That's what it is," essentially means, "This is the state of things, and that's that" or "This is how it must be."
What Does 'I Heard You Paint Houses' Mean?

This was the title of the Frank Sheeran memoir on which The Irishman is based. Does it refer to an honest job one does to avoid a life of crime?
No, it does not.
What 'I Heard You Paint Houses' Means

Here's Frank Sheeran in I Heard You Paint Houses, recounting his first conversation with Jimmy Hoffa (played by Al Pacino in The Irishman):
“The first words Jimmy ever spoke to me were ‘I heard you paint houses.’ The paint is the blood that supposedly gets on the wall or the floor when you shoot somebody."
Which brings us to our next mob movie slang.
What Is 'Carpentry' in a Mob Movie?

Sounds nice, right? Couldn't possibly have some violent secret meaning.
What Carpentry Is in a Mob Movie

Sheeran also says he told Hoffa in their first conversation: "‘I do my own carpentry work, too.’ That refers to making coffins and means you get rid of the bodies yourself.”
And as we saw in The Irishman, Frank Sheeran can also drive a truck.
Wow, what can't this guy do?
What Does It Mean to 'Go to the Mattresses'?

Fans of The Godfather will know this one. It isn't quite like sleeping with the fishes, but you might end up sleeping with the fishes if you don't go to the mattresses.
What It Means to 'Go to the Mattresses'

When you go to war with a rival or clan, you'll want to hide in a secret, secure location with all your mob buddies, living with only the bare essentials. That means sleeping on mattresses on the floor, not in a soft comfy bed with your wife or gumar.
One big plus of going to the mattresses: If someone shoots through the windows, you'll be nice and low to the ground.
How Many of These Phrases Did You Know?

9 correct... The Godfather
6 correct... Made man
3 correct... schnook
1 correct... fughetaboutit
Liked This List of Mob Movie Slang Phrases Explained?

You might also like this list of TV Shows With Unlikable Lead Characters, including the reputed head of the Soprano crime family (above, from HBO.) Or this list of Gen X Film Stars Who Died Too Soon.
Main image: Goodfellas, from Warner Bros.