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.
* AbusiveParents: As Homer points out, Abe's been an awful father. 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. 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. [[JerkassRealization Abe does regret how he treated Homer later on]].
* AdviceBackfire: 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". HilarityEnsues.
* AwLookTheyReallyDoLoveEachOther: 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.
* BaitAndSwitch: When Lisa and Bart buy some books, with Lisa buying one by UsefulNotes/AlGore and 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 Gore... that somebody finally bought his book.
* BaitAndSwitchComment: 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.
* BalloonBelly: 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.
* BrakeAngrily: Homer does this right after Abe tells him his birth was an accident.
* CarFu: 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.
* ContinuityNod: Marge mentions [[Recap/TheSimpsonsS3E12IMarriedMarge Bart's birth being an accident]] as well.
* DidNotThinkThisThrough: 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.
* EpicFail: 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.
* FlatJoy: 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''': ''[[https://en.wikipedia.org/wiki/Celebration_(Kool_%26_the_Gang_song) Ce-le-brate good times, come on!]]''
-->'''Gore''': (still monotone) I will.
* ForgottenPhlebotinum: 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".
* GetOut: Homer kicks his father out of the car after he is told that his birth was an accident.
* IfItsYouItsOkay: Homer tells Marge a father shouldn't tell his own son his birth was an accident. Marge reminds him he says it to Bart all the time, but Homer says when ''he'' does it "it's cute".
* LeftTheBackgroundMusicOn: 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.
* OOCIsSeriousBusiness: 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 TranquilFury 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:''' (''[[BrakeAngrily 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.''
-->'''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''.
* RamblingOldManMonologue: 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...
* SarcasmBlind: 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.
** Bart writes on the chalkboard that his homework wasn't stolen by [[Series/TheFugitive an 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.
* SnakeOilSalesman: 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.
* SpannerInTheWorks: 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.
* TheCasanova: Professor Frink becomes this as soon as he drinks the tonic, and he picks up a female scientist.
* TheConspiracy: The children of Springfield suspect something huge is going on involving "reverse vampires" because their parents rush home before nightfall. They are actually just having sex.
* TranquilFury: Homer when Abe calls him an accident. It [[OOCIsSeriousBusiness scares Abe]] into apologizing, to no avail.
* WeekendInventor: 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 [[Recap/TheSimpsonsS3E10FlamingMoes Homer came up with the flaming Homer]].
* WhatHappenedToTheMouse: 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. The writers edited this out because they didn't think Ralph would be smart enough to understand that.
* YouCantGoHomeAgain: 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. [[FromBadToWorse Then they accidentally burn it down]].
* [[YouShouldHaveDiedInstead You Were An Accident]]