SNL Surprise

Taylor Swift crashed "Saturday Night Live" on Saturday, stepping onstage during Dakota Johnson's opening monologue, NBC News reported.

Sunday, Johnson turns 37. Swift returned during the show's curtain call to hand her a blue and white birthday cake, according to NBC News and Deadline.

Johnson had spent her monologue riffing on her recent breakups with musicians Chris Martin and Role Model, comparing the whole messy experience to her new film, "Verity." "The movie is a psycho-sexual erotic thriller, and you know what? So is dating musicians," she joked, according to Rolling Stone. "Some people leave concerts with merch and I leave concerts with a two and a half year relationship," Johnson added, according to Deadline. "But I have really good friends. They don't judge me for dating these men. They're actually really supportive." She called Swift her "literal therapist."

Swift disagreed. "I'm not your therapist, actually," she shot back, according to NBC News. "You just show up once a week at my house with an empty bottle of wine and ask if I want some." Johnson didn't flinch. "Yeah, well, I have manners," she replied.

The onstage bit followed Johnson's appearance in the video for Swift's "Patient Zero," which Swift directed, Bleeding Cool News reported. Rumors of a cameo had circulated all week, tied to the pair's friendship and Johnson's birthday, Bleeding Cool News reported ahead of the broadcast. Saturday was Johnson's third time hosting "SNL" overall and her second episode this season, following a debut in season 40, according to Deadline. The Guardian reported Swift's entrance drew a loud response from the studio audience, though its review of the full episode rated the night weak overall and described Johnson's grip on live comedy as uneven. Turnstile played as the night's musical guest, NBC News reported.

Swift sketched out a typical night with Johnson. "You flop on my couch and overshare, and every so often I just say, 'Damn, that's crazy,'" she said. No sleepover. Just Pedialyte and a ride home from her security detail. "Sleepover, yay!" Johnson said anyway, according to NBC News.