After getting busted on a DWI ("driving while intoxicated," not DOA ["dead on arrival"], as Chief Wiggum learned) charge[[note]]even though he passed the road test before Barney told the cops to give him a Breathylizer test, and Barney was never arrested either, since he drank almost as much as Homer did[[/note]] after sneaking out of work to go to a Duff Beer Factory tour, Marge urges Homer to go 30 days without beer. Meanwhile, Bart destroys Lisa's steroid-injected tomato and becomes an unwitting test subject in her new science fair project: "Is My Brother Dumber Than a Hamster?"

!!Tropes featured:

* ActorAllusion: Lisa says she was chuckling over a joke from ''HermansHead''. Yeardley Smith was an actress on that show as well (even though she and fellow ''Simpsons'' voice actor HankAzaria don't like to acknowledge that they were on ''Herman's Head'').
* BedtimeBrainwashing: The episode opens with Principal Skinner awarding Bart first prize at the school science fair. The phrase "first prize" echoes until the scene transitions to reveal that Lisa was saying this into Bart's ear while he was dreaming because she was "just screwing with [his] mind."
* DeadBabyComedy: Chief Wiggum confusing DWI with DOA. Also Homer laughing at the montage of car wrecks (and Troy [=McClure's=] attempts to make jokes during it).
* KarmaHoudini: Barney gets away with essentially kicking off the episode's main plot by urging the police to give Homer a breathalyzer test right after he flawlessly passed a field sobriety test. After failing the breathalyzer test, the clearly sober-enough-to-drive Homer is arrested, stripped of his driver's license, forced to attend AA meetings, and gets into a bet in which he can't drink beer for a month; meanwhile, the obviously skunk-drunk Barney is allowed to drive off, even knocking one of the cops off a cliff as he speeds away.
* LeaningOnTheFourthWall: At the end of the episode, when Homer leaves Moe's bar to go on a bike ride with Marge, Moe proclaims "You'll be back. And so will all of you, and you... and ''you''," whilst looking and pointing directly at the viewer, [[FourthWallPsych before quickly cutting to a different shot to show he was talking to Barney]].
* YoungerThanHeLooks: Hans Moleman is revealed to be 31 years old and looks old because of severe alcoholism. Before anyone cries "NegativeContinuity!", this does tie in with the birth date on his driver's license, as seen in "Selma's Choice," which is August 2, 1961 (which would make him around 31 to 32 years old at the time of this episode's premiere).