When Homer and Marge try and fail to reinvigorate their fading sex life, salvation comes in the form of Grampa Simpson, who concocts a bathtub aphrodisiac that Grampa and Homer sell to the masses. Meanwhile, Bart fears that the alleged disappearance of all the adults is part of an alien invasion/government conspiracy.
- Abusive Parents: As Homer points out, Abe's been an awful father who was never supportive. When Homer was watching President Kennedy on television as a child and imitates him, Abe cruelly tells Homer (while rolling up a newspaper) that America was made so idiots like Homer can't be President and to stop daydreaming. Then there's the entire car argument where Abe flat-out tells Homer that he was an accident and that he never should have been born. Abe does regret how he treated Homer later on.
- Advice Backfire: Homer and Marge initially try to rejuvenate their sex life by following the advice of a book on tape entitled "Mr. And Mrs. Erotic American". Hilarity Ensues.
- Attention Deficit... Ooh, Shiny!: Homer trying to explain the situation with Abe gets distracted by a chocolate bar Bart's eating, but Homer tells him to put it away.
- Aww, Look! They Really Do Love Each Other: Homer and Abe make amends with one another.Homer: I'm a screw-up. I burned down our house.
Abe: No, I'm a screw-up. I burned down our house.
Homer: You know what?
Homer: We're both screw-ups.
- Bait-and-Switch: When Lisa and Bart buy some books, with Bart buying one about UFOs, the library scanner sends a signal to a satellite, which sends it to the US Pentagon, and it's printed out. An Army officer looks over it, and immediately hurries to the White House, reporting to Al Gore... because Lisa just happened to have bought his book as well, and is in fact the first person to do so.
- Bait-and-Switch Comment: After Homer stops helping Abe to sell the aphrodisiac, Abe tries to get Barney's help and later says it's not the same without Homer. Homer can drive.
- Balloon Belly: Homer ends up looking even fatter than usual after spending the night engorging on enchiladas, much to Marge's disappointment, as she was in the mood to snuggle.
- Brake Angrily: Homer does this right after Abe tells him his birth was an accident.
- The Casanova: Professor Frink becomes this as soon as he drinks the tonic, and he picks up a female scientist.
- Car Fu: When "Mr. And Mrs. Erotic American"'s advice doesn't work out for Homer and Marge, Marge throws the tape out the car window. Homer then crushes the tape by running the car back and forth over it.
- The Conspiracy: The children of Springfield (except Lisa) suspect something huge is going on involving "reverse vampires" because their parents rush home before nightfall. They are actually just having sex.
- Continuity Nod: Marge mentions Bart's birth being an accident as well.
- Did Not Think This Through: Planting Homer in the audience to sell the tonic fails not only because of Homer's lousy acting skills but also because Homer's face is in the tonic's label.
- Epic Fail: Homer's attempts to be a good father to Bart and Lisa all fail spectacularly because he smothers them and won't listen to their objections. Bart even tells him that they far preferred it when he wasn't trying to be a good father to them.
- Flat Joy: Al Gore was really excited that someone bought his book.Gore: (smiling; monotone) Well. (reaches over to a record player; turns it on) This calls for a celebration.
Record Player: Ce-le-brate good times, come on!
Gore: (still monotone) I will.
- Forgotten Phlebotinum: Grandpa's tonic sure would've helped in later episodes where Homer and Marge's sex-life was struggling, e.g. season 9's "Natural Born Kissers".
- Free-Range Children: After Homer gets his sexual drive from the tonic, he gives his children fifty dollars and tells them to go to the movies, then take a cab to their aunts' house. The kids promptly head over to a Stock Footage festival.Lisa: What do you think Mom and Dad are doing right now?
Bart: I don't know.
- Get Out: Homer kicks his father out of the car after he is told that his birth was an accident.
- If It's You, It's Okay: Homer tells Marge a father shouldn't tell his own son his birth was an accident even if it's true. Marge reminds him he says it to Bart all the time, but Homer says when he does it "it's cute".
- Left the Background Music On: When Homer and Abe are fleeing an angry mob, Homer tells Abe that the mob only started chasing them after the music started. Homer is proven right when he turns the music off.
- O.O.C. Is Serious Business: Normally, when Homer's mad, he'll explode at you. Abe's "You were an accident!" comment evidently hurt him enough to put him in Tranquil Fury mode.Abe: If I hadn't taken that tonic 38 years ago, you would never have been born and I would be happy! You were an ACCIDENT!
Homer: (slams on the brakes and speaks very softly but still evidently enraged) Get out.
Abe: (genuinely concerned) I'm sorry I said that...
Homer: (still softly) Out.
- Parental Sexuality Squick:Abe: Unsatisfying sex life?
Homer: N— yes! But please, don't you say that word!
Abe: What, "seeeex"? What's so unappealing about hearing your elderly father talk about seeeex? I had seeeex.
- Rambling Old Man Monologue: Grampa is in rare form when he's riding in the car with Homer:Abe: ...And that's what's wrong with Bart's generation. Now, as for your generation...
- Sarcasm-Blind: When Lisa jokingly suggests that the adults of Springfield have become reverse vampires who have to get home before dark, all the other kids become terrified of the idea, and instantly accept it. Much to Lisa's annoyance.
- Sesquipedalian Loquaciousness: After noticing something is wrong with Marge, Grampa speculates that she might be suffering from pneumonoultramicroscopicsilicavolcanoconiosis.
- Bart writes on the chalkboard that his homework wasn't stolen by a one-armed man.
- After years of Professor Frink as Jerry Lewis' Nutty Professor character, we see him as Buddy Love after he drinks the tonic.
- Snake Oil Salesman: Homer and Grampa's traveling show has all the hallmarks of this, including old-fashioned barking from a platform, and planting people in the audience, but the tonic really does work in this case...until the duo break up.
- Spanner in the Works: Homer and Marge try to have a romantic getaway at the Aphrodite Inn, a hotel that offers guests themed rooms for their erotic fantasies, such as the Caveman Room, the Pharoah's Room and the Camelot Room. Unfortunately, almost all the rooms are taken when Homer and Marge check in, forcing them to stay in the Utility Room. Homer tries to play it up as a romantic fantasy where he's the janitor and Marge is the janitor's wife, but Marge points out that it really is the hotel's utility room. At one point, the desk clerk comes in to get a vacuum cleaner.
- Sure, Let's Go with That: When Bart is freaking out over thinking the umbrella in the tree was UFO, and Marge refused to let him sleep with her and Homer.Bart: Can I sit on the roof with a baseball bat in case a UFO does come?
Marge: Yes, yes, yes, that's fine. Good, good.
- Tranquil Fury: Homer when Abe calls him an accident. It scares Abe into apologizing, to no avail.
- The Unreveal: A flashback shows us a rare glimpse of Homer's mother... from the neck down, so we don't see her face (for another year or so).
- Weekend Inventor: Grampa Simpson managed to come up with a fast acting aphrodisiac out of random things he had lying around (that was originally supposed to be a cheap substitute for holy water), similar to how Homer came up with the flaming Homer.
- What Happened to the Mouse?: The kids spying on their parents plotline fades out eventually. A deleted scene had Ralph telling them that the parents aren't around because they're busy having sex (a revelation which Bart then twists into a conspiracy involving the Mole People). The writers edited this out because they didn't think Ralph would be smart enough to understand that.
- You Can't Go Home Again: Homer and Grampa go back to their old farm, and recollect happier times (and unhappy times), but it's worn down and just not the same. Then they accidentally burn it down.
- You Should Have Died Instead: Abe telling Homer that he was an accident is the same principle.