Lisa becomes smitten with an older musician named Brendan (voice by Ed Sheeran), sparking a jealousy in Nelson, who uses jazz to try and win her over instead. Meanwhile, Homer and Marge worry when Bart discovers his affinity for chemistry.
Tropes:
- Brilliant, but Lazy: Bart initially dismisses chemistry as lame but once he understood what he could do with chemistry (and the kind of pranks he could pull) he quickly excels and starts assimilating all sorts of chemistry activities he can.
- Cock Fight: Nelson and Brendan start trying to one-up each other musically to win Lisa over.
- Comically Missing the Point: Chief Wiggum doesn't understand what anonymous means and tells who made the anonymous report he's responding to (Principal Skinner).
- Continuity Nod: The opening number references the Crazy Cat Lady's legal career as seen in "Springfield Up."
- Crazy Jealous Guy: Nelson becomes jealous of Brendan who is the current object of Lisa’s affections.
- Disqualification-Induced Victory: Nelson gets this in the talent show when Brendan is disqualified for not living in Springfield Elementary School's district.
- Easily Forgiven: Groundskeeper Willie is responsible for the sulfuric acid incident that made Superintendent Chalmers lose the tip of his tongue but Chalmers forgives him when he says he was trying to kill Principal Skinner. Even Agnes admires Willie for having a dream to kill Seymour.
- Funny Background Event: During the epilogue, Groundskeeper Willie is briefly seen trying to spike a drink with acid again.
- Gave Up Too Soon:
- Had Homer and Marge stayed looking at Bart's treehouse for a few more seconds, they wouldn't have missed the results of the experiment he was performing there.
- Inverted later on when Marge finally trusts Bart in his experiment at school, but then he tells her she shouldn't have, right before the whole school is filled with pink foam.
- Imagine Spot: Lisa imagines how her life will be if she marries Nelson.
- Leaning on the Fourth Wall: The Simpsons' garage contains a box labeled "COUCH GAG PROPS / USED."
- Love Triangle: Lisa gets stuck in a love triangle that involves Brendan, a new guy with a talent for music, and Nelson, her ex who is trying to win her back.
- Jerkass Gods: God crushes everyone who participated in the opening number with his thumb, except Lenny, who takes it all in stride. Though Negative Continuity means that they're back again later in the episode.
- Jerkass Has a Point: Instead of encouraging his son's budding interest in chemistry, Homer takes it for granted that he's planning a prank. Which he is, of course.
- Mistaken for Pedophile: The chemist who helps Bart become interested in chemistry is initially mistaken by Bart for a child molester, as the man asked Bart if he'd like to see something and Bart replied by worriedly asking if the man was a pervert.
- Never Recycle Your Schemes: Averted. Groundskeeper Willie makes another attempt to kill Principal Skinner with acid.
- No Sympathy: When Groundskeeper Willie admits he tried to kill Principal Skinner, Superintendent Chalmers and Skinner's own mother were okay with it.
- Not Me This Time: Bart isn't behind the sulfuric acid incident. He is, however, responsible for filling the school with pink foam.
- Paper-Thin Disguise: Mr. Burns' booth has him try to convince people that nuclear power is safe and reliable by having Smithers disguise himself as a scientist by wearing a lab coat, a monocle, and a fake mustache.
- Senseless Violins: Subverted. At first it looks like Nelson and his gang are bringing weapons inside the cases to beat up Brendan, but it turns out they are carrying actual instruments for serenading Lisa.
- Shout-Out:
- The title and the opening musical number allude to La La Land.
- Homer asks Bart "are you Breaking Bad in here?"
- Skewed Priorities: When Ralph shows up at school with his father's cap and gun, Chief Wiggum is more concerned about the cap.
- Starving Artist: Brendan has a credit card but has no money. Lisa says the last part is like every artist.
- Suicide as Comedy: Bored at the science expo, Bart cheerfully approaches a booth and says, "One child, please." We then see that the booth reads ASSISTED SUICIDE.Disco Stu: I was here first. If disco's dead, I don't wanna live. It's Stuicide!
- Take That!: Marge apologizes to the viewers because the episode was supposed to parody Moonlight instead of La La Land but Homer tells her nobody watched Moonlight. Marge offers to let people watch it on DVD but Homer and everyone else but Lisa say they'd rather watch X-Men: Apocalypse.
- Wingding Eyes: Brendan, Nelson and Lisa get these (their pupils becoming a music note, a boxing glove and a hung angel repectively).
