I see a lot of headcanons and stuff about Nico having a potty mouth and cussing a lot, but let me tell you, I really don’t believe Mama di Angelo would even let ‘damn’ slip out of his lips before she’s washing his mouth out with soap.
He probably never even thinks of swearing because of how he was brought up, even in the midst of a deadly Mario Kart race against Jason and Percy.
But Will is a complete potty mouth, having grown up in the Apollo cabin with his older brothers. And at first, Nico is a little bothered by Will’s habitual swearing, and tells him to ‘shut up’, to which Will replies ‘make me’.
And Nico totally does by putting Will’s mouth to better, and more pleasurable uses.