Halloween is a day of observation that is normally celebrated by humans and Smurfs alike, usually in the form of people going about in costumes doing trick-or-treating.
Comic Book/2021 TV Series Universe[]
A special comic book published by Papercutz, The Smurfs Halloween, has two stories set in the comic book universe that take place during that day. In the comic book story "Halloween", the Smurflings use pumpkins as masks to go trick-or-treating and scare a witch whose apple tree they were eating fruits from, with the witch threatening to turn them into pumpkins.
Halloween would also be celebrated in a one-page gag featured in Schtroumpferies.
In the 2021 cartoon show episode "The Scariest Smurf", Gargamel gets into the act of getting dressed up for the holiday, choosing to go as Brainy Smurf while he hands out treats to passersby. In the episode "The Magic Pumpkin", Wimpy attempts to scare the whole village with a magical pumpkin given to by Smurfette, though it is not magic at all.
1981 TV Series Universe[]
In the 1980s cartoon show universe, it is also the day of Jokey's birthday, which the Smurfs celebrate by letting him offer all his fellow Smurfs his "surprises" by going through the alphabet of Smurf names, as it is Gargamel's birthday, a fact that he greatly despises. Hogatha the witch calls Halloween her favorite day of the year because she gets to scare little children. On one particular Halloween in the episode "All Hallows' Eve", Lazy was accidentally turned red by Mother Nature who was using her red magic wand to turn the leaves of the Smurf Forest red, and was unable to change Lazy back without the additional help of Father Time, who used his powers over time as well as Mother Nature's magic wands to restore Lazy's original appearance.
Because that day is reserved for celebrating Jokey's birthday in the 1980s cartoon show, a similar day of observation called Spook-A-Smurf Eve is held presumably around that same time period.