Lucifer has never been afraid to toe some dicey territory. It's a show full of sex, drugs and rock 'n' roll; however, one notably "adult" aspect has been mostly missing: expletives. The show, which is based on the Lucifer Morningstar character (created by Neil Gaiman, Sam Kieth, and Mike Dringenberg for DC Comics), aired on FOX for Seasons 1-3, meaning that explicit language was heavily censored. With the jump to Netflix with Season 4, fans expected the show to get a bit raunchier. However, the show's writers kept the language mostly tame to fit the tone of the initial run of episodes. In Season 5, though, an f-bomb is finally dropped.
In Season 5, Episode 12 (titled "Daniel Espinoza: Naked and Afraid"), Dan Espinoza (Kevin Alejandro) is thrown in a nightmare of a week, getting caught up in disastrous situations that lead up to a tragic shootout. In the end, though, it's revealed that it was all an elaborate prank by Lucifer and everyone is alright.
As a party is kicked off, Dan and Lucifer sit at Lux's bar to grab drinks. Dan thanks Lucifer for the experience, realizing he needed to go through it to come to terms with his past. Lucifer is extremely disappointed in hearing this, and Dan wants to know why Lucifer did it, if not to help him. Lucifer replies, "Because you f—ing shot me Daniel."
This line of dialogue was a reference to Season 5, Episode 7 ("Our Mojo"), where Dan, reeling from discovering Lucifer is the devil, shoots our protagonist. It seems this frustrating situation and an unsuccessful revenge prank are justification enough for the show's first f-bomb.
Back in 2019, co-showrunner Joe Henderson explained why they're hesitant to include too much language, despite the freedom Netflix provides. "We tried an F-bomb (in Season 4) and it just felt a little weird," he told TV Line. "It was good that we tried it, because we sort of wanted to see how it felt. It's like when you get a toy and you start playing with it, and then you start to realize that maybe this toy, as fun as it is to play with, isn't the right toy to play with on the show. Families watch our show, like older families, and while we wanted to both make a show that pushed the boundaries, we also didn't want it to feel unnecessarily profane. We did say 's—' a couple times. And we used a 'bulls—' when absolutely necessary, or we tried to."