
Talk dirt
Use gross language / Have a dirty mouth / Have a mouth like a truck driver

Parlare grasso 
Use gross language / Have a dirty mouth / Have a mouth like a truck driver

Parlare grasso 
Meanings
To speak using vulgar, rude and offensive words
Examples
I don't like your new friends; they always talk dirt even in front of the children
Non mi piacciono quei tuoi nuovi amici, parlano sempre in modo volgare anche davanti ai bambini
Maybe I'm a stick-in-the-mud, but people talking dirt bother me
Non sarĂ² al passo con i tempi, ma mi danno fastidio le persone che parlano grasso