Kristen Arnett isn’t a dad, but she plays one on Twitter. The “With Teeth” author may not evoke traditional fatherly traits — she is, after all, a lesbian with no children — but she has an arsenal of terrible jokes, like the one about the best time to go to the dentist.

“That’s tooth-hurty,” she said during a recent interview. “And if your friend needs to go as well, then that’s tooth-hurty-two.”

As Father’s Day approaches, Arnett is stepping in as a self-appointed “gay dad” to people online who need one. For those who have lost fathers or have difficult relationships with them, Father’s Day can be a painful reminder of missing out: all of the tributes on social media with sappy captions and endless advertisements for shaving cream and hardware, depicting idyllic parental bonds. Arnett is estranged from both her parents, so she knows how hard this time of year can be, especially amid the pandemic, when family absences and rifts have been exacerbated.

Her brand of fatherhood, in some ways, reflects cultural norms: She tweets about her interest in yardwork and beer. And she provides encouragement, kindness and a receptive ear for people in similar family situations. Last year, a Twitter follower with an unaccepting father came out to Arnett as bisexual for Father’s Day. People wanting more privacy directly message her, sharing stories of their own estrangement and loss and how much they appreciate her acceptance and care.

“It’s just a general feeling of camaraderie and unfailing support,” she said. “Maybe I don’t know what you’re doing all the time or understand it, but I support you, bud.”

Arnett’s friends in real life drew her attention to her dad-like behavior years ago, picking up on her bad puns, baseball caps and beer, before she started to lean into the persona, wearing a hat that was gifted to her with “FUN DAD” printed on the front. One of her earliest tweets, in 2018, was a selfie of her holding a can of Steel Reserve next to her French bulldog, Lola, captioned “dad says hi.”

Then, the running joke turned into a way to support others. Similarly to comedian Josh Gondelman’s spontaneous pep talks on Twitter, Arnett started to engage with her audience as if she were a little league coach, calling her 60,000-plus followers “champ” and “pal” during surprisingly fulfilling interactions.

Now, many of her followers casually call her “dad.” So she reaches out to them specifically for Father’s Day to make the day brighter for those who need it. It might not be a typical father-child relationship, but it has proven beneficial to both parties.

“I had a person who follows me whose parent had died within the last four months who said, ‘This was the first post I saw that didn’t make we want to cry,’ ” Arnett said. “It just made me feel good.”

It’s a queer twist on the anonymous parenting and gentle encouragement that’s emerged online, in the vein of the “Need a Dad for a minute?” subreddit, where people seeking advice or support talk to other users taking on the role of pretend parents.

“Most of the time people just want some encouraging word or to feel like someone else is there,” she said. “I know as a person who wants this for myself, that’s just a human need.”

This year, a week before Father’s Day, Arnett gave away 10 copies of her new novel “With Teeth,” released this month by Riverhead Books. The resonance of gifting this book — an occasionally violent portrait of complicated queer family dynamics stripped of sentimentality — to those with difficult or distant relationships with their dads isn’t lost on her.

“This is a book about mess, and we’re all kind of in a mess together,” she said. “I hope people are able to look at that and see a little bit of their own mess in there, and see other people’s, and see that it’s okay.”

Arnett’s own plans for Father’s Day consist of drinking a couple sweaty beers outside — maybe a Florida-brewed Jai Alai IPA — and thinking about the fulfillment of being, if only for a few tweets, the dad she wishes everyone got to have.

“It’s a gentle little reminder that you’re not alone,” she said. “There are people who care about you, even if you don’t have a father in your life; there are people who can fill those roles and actually do care.”