Here’s a fun passage in Dashiell Hammett’s ‘The Gutting of Couffignal’, a great story that opens The Big Knockover and Other Stories (whose colourful crooks’ names I listed recently). Skip the first paragraph if you want to avoid spoilers.
‘There’s your choice, Flippo,’ I summed up for him. ‘All I can give you is freedom from San Quentin. The princess can give you a fat cut of the profits in a busted caper, with a good chance to get yourself hanged.’
The girl, remembering her advantage over me, went at him hot and heavy in Italian, a language in which I know only four words. Two are them are profane and the other two obscene. I said all four.
Profanity is when something is considered insulting to a religion, its god(s), or people’s beliefs in them. Obscenity involves offense to taste or common decency, something vulgar enough to be taboo in a given context (often relating to sex or bodily functions). There are legal nuances to both terms, but I won’t get into that here.
Two profane and two obscene words, all presumably common swears, or common in the early 20th century. I can guess what they might be, but maybe Hammett didn’t have four particular words in mind. There are Italian speakers in my family; I’ll run it by them. For research.