Chilling Adventures of Sabrina's final set of episodes are all about the Eldritch Terrors. At the end of Part 3, Father Blackwood released several of them into the world, and Part 4 is all about reining them back in. Although author H.P. Lovecraft created hundreds of these Terrors in his written works, there are eight in CAOS, all told. (One per episode — so convenient.) As usual, all of these Terrors aim at Sabrina. That includes The Weird, a parasite that attempts to take Sabrina over as a host. To hold onto herself during the exorcism process, Sabrina sings a cute little ditty. And Sabrina's "16 Going On 17" song in Chilling Adventures might ring a bell for viewers.
Warning: Spoilers for Chilling Adventures of Sabrina Part 4 follow. Even though there have been two seasons (split across four "parts," of Netflix's Sabrina), the entire series follows a year of her life. In the premiere episode of Season 1, it's about to be Sabrina's 16th birthday. As Part 4 draws to a close, her 17th birthday arrives. It's been an eventful year to say the least, but nothing quite matches losing her inner self to a parasite Terror that wants to use her to take over the world.
As the exorcism commences, Ambrose tells Sabrina she needs to hold on to herself, lest she too is drawn out of her mind. So, Sabrina decides to sign the Rodgers and Hammerstein song "16 Going On 17." Perhaps it's due to her age, or maybe just Zelda and Hilda's taste in musicals, but Sabrina's song choice is a perfect fit for the moment and even has a duet in which Nick can join in and sing along too.
The song is one of Broadway's most famous love songs, from 1959's The Sound of Music. In it, Liesl has a crush on Rolf, who is a year older than her. He lords this fact over her, but she pertly sings back that as someone in need of guidance, she's perfect for him.
(Ironically, Rolf winds up rejecting Liesl, and in the stage version, there's a reprise she sings with Maria as she works through her broken heart. It was left out of the movie version with Julie Andrews, though, so it is less well known.)
The song has been played in countless TV series and films, including the 2004 film 13 Going on 30, which contains a reference to the song right there in its title.
Though Nick has never lorded his age over Sabrina, the song is a cute fit for the on-again-off-again couple. And it helps build toward Nick's choice in the following episode to win Sabrina back.