Most item descriptions in general. Seriously, go read them. Some are fairly straight forward descriptions, while others range from being sarcastic to just being a chuck load of pop culture references.
What happened to the Wings of Eldon series, especially "Eldon: Doom/Reborn" and "End of Eldon"
Vacation of Eldon: "A side story to the popular series. Cuto and Eldon get some well-deserved R&R...and beach babe time." Even though the series is (presumably) not illustrated, considering End of Eldon is 2000 pages long.
The joke gets even funnier when you realize the titles Doom/Reborn and End of Eldon are a spoof of the Neon Genesis Evangelion movie titles.
The first time Recette utters her cheerful Catch Phrase, "Capitalism, ho!"
And then there's Alouette's twist on it should you actually overcharge her: "Such naked avarice. Capitalism ho, indeed."
Recette covertly tries to find out why Caillou hangs around the orphanage, hiding behind what a taped on piece of paper helpfully indicates is "totally a tree".
Recette: We got you surrounded! Yes, the toy soldiers totally count!
Recette fearing the theft of her cuteness.
The abrupt manner in which Tielle's missing big sister's storyline is brought to a close (via a Well Done Little Sister Gal style letter).
Recette and Tear opening shop one morning, then having a conversation in a shocked, awestruck manner, sounding like they've just seen the coming apocalypse... Nagifinally made it in the door!
"It finally happened..." "I didn't think it would be so soon..."
Some of the items your customers buy can look very out of place considering their age and gender sometimes. For example, one can wonder what "experiments" Caillou actually needs a schoolgirl uniform for... Or why a housewife has been so desperately looking for an exclusive dagger, for that matter.
The funniest one is easily the little girl purchasing a copy of "Booze of the World".
Or a woman coming in with the comment "My husband was hiding this in the den. How. much." The item? A sailor suit. Or a novel titled Puresoul Diaries. Or, far more commonly, junk food.
Similarly, the old man buying the aforementioned sailor suit.
"Heh heh, I've been searching for one of these..."
Man: "My wife asked me to pick this up." Item: Club... DOMESTIC ABUSE, HO!!
Or when the old men mention their grandkids pestering them to get something...like food, or, even more worryingly, a vial of powerful antivenom.
Or when somebody claims that what they're trying to sell to you is a family heirloom...Said "what" being A bar of chocolate.
Louie: This is a family heirloom! ... so it'll go for more, right?
Or, once you buy the treasured heirloom that their grandma gave them on their deathbed or whatever:
Man: Wow, even stuff like this sells!
Or when Louie tries to sell you something he says he found while cleaning out his house. Said something being a ham sandwich.
It is highly, HIGHLY unlikely that all the people claiming they are buying gifts are really buying gifts. Unless you really believe that upon an announcement that reading has become popular with young girls, the store has really been hit by a flood of girls buying presents for their entire families and, occasionally, themselves.
Griff's default equipment includes cute little green summer sandals.
Griff: What. Is. This. That idea is so disconnected from reality that I cannot tell whether you are mocking me or trying to be profound. And...failing. Badly. Speak plainly.
Griff: People with a worldview as distorted as hers form religions. BAD ones.
When Griff finally becomes one of your customers he has some amusing quotes:
Griff: Sell this to me! I DEMAND IT!... Politely, that is.
When an item or item group is currently "in" with some of the towns people, it pays (quite literally) to provide that item in bulk and show it in all possible spaces at the windows. Watch the hilarity ensueing! The music absolutely sells this kind of event.
Announcer:Old men have come in great numbers, looking for the popular Worn Sword!