"I thought nothing could be as bad as red hair. It turns out green is ten times worse."
Anne and her friends acting out "The Lady of Shallot." It all goes well until the boat sinks...
Anne accidentally getting Diana drunk. Though the consequences aren't funny, the event itself is. What she thought was raspberry cordial turned out to be currant wine, and Diana drank three tumblerfuls of it. Note that homemade wine back then was much more potent than we would assume today, as they had no way of regulating the alcohol content...
Anne makes a cake for a guest, but accidentally uses muscle linement instead of vanilla extract. Anne had a cold and couldn't smell the difference.
Anne's first attempt at praying. And remember that the book was published in 1908, when this kind of humor about religion was a lot more shocking.
Anne's Backhanded Apology to Mrs. Lynde, making sure to slip in that all the insults she's apologizing for were true, but she still shouldn't have said them.
The fact that Mrs. Lynde doesn't notice this...but Marilla does. She also realizes Anne's enjoying it, and yet figures she can hardly scold her for apologizing "too well".
Anne of Avonlea
Mr. Harrison, Anne's irascible new neighbour, tells her to stop letting her cow get into his garden. Shortly afterwards, Anne sees a cow that looks just like hers in his field, thinks her cow has escaped again, and goes to chase it. By the time she catches the cow, she's so thoroughly out of sorts that she promptly takes the opportunity to sell it to Mr. Shearer on the spot. Only afterward does she discover that her cow is right where it was supposed to be - the cow she sold was actually Mr. Harrison's own cow. Fortunately, Harrison takes this all with reasonably good grace when Anne goes to explain and apologize.
Anne, Marilla and Diana all put a spoonful of sugar in the pot of peas because each was afraid the others would forget about it. They only discover the truth when Anne tastes the peas. The narration goes on to note (paraphrased), "There were no peas at dinner that day."
Anne of the Island
The girls of Patty's Place trying to humanely chloroform a stray cat, by sealing it in a wooden box... which they totally forget to check for knotholes.
"Why in the world don't you come?" demanded Stella, appearing in the doorway. "We've got the grave all ready. What, 'silent still and silent all?' she quoted teasingly.
"'Oh no, the voices of the dead/Sound like the distant torrent's fall,'" promptly counter-quoted Anne, pointing solemnly to the box.
Rilla of Ingleside
Miranda and Joe's wedding. Miranda's father, Mr. Pryor AKA Whiskers-On-The-Moon, doesn't want Miranda to marry Joe because Joe's a soldier and Whiskers is a pacifist, so Rilla organises their wedding at Ingleside. The wedding is eventful; during the ceremony Miranda's dog has a fit, and at the reception Joe's mother sits on a pie!
During the preparations for the wedding, Rilla asks Susan to make a wedding cake... before telling her about the wedding.
"A wedding-cake!" Susan stared. Rilla had, without any warning, brought her a war-baby once upon a time. Was she now, with equal suddenness, going to produce a husband?
Whiskers-On-The-Moon gives an anti-war prayer at a prayer meeting organised to pray for the soldiers. Norman Douglas objects: he gets up and shakes Whiskers-On-The-Moon.
"You blatant beast!"—shake—"You malignant carrion"—shake—"You pig-headed varmint!"—shake—"you putrid pup"—shake—"you pestilential parasite"—shake—"you—Hunnish scum"—shake—"you indecent reptile—you—you—" Norman choked for a moment. Everybody believed that the next thing he would say, church or no church, would be something that would have to be spelt with asterisks; but at that moment Norman encountered his wife's eye and he fell back with a thud on Holy Writ. "You whited sepulchre!" he bellowed, with a final shake, and cast Whiskers-on-the-moon from him with a vigour which impelled that unhappy pacifist to the very verge of the choir entrance door.
Gilbert's reaction to this.
"...Norman's performance was utterly improper and scandalous and outrageous; but, by George,"—the doctor threw back his head and chuckled, "by George, Anne-girl, it was satisfying."