Smurfy Friendship Day

Smurfy Friendship Day is a day observed by the Smurfs in the cartoon show episode "Chlorhydris' Lost Love". It is similar to the human observance day Valentine's Day in which the Smurfs give valentine-style cards to one another in friendship and love. (Though no month has been shown for when it falls on, its date is the 14th of the month, and judging from the climate condition in the episode, it is presumably sometime from April to August.) It is also when Cupid the ambassador of love comes around to shoot his arrows at creatures and living beings so that they could feel and express love toward one another.

On that particular day in the episode, Chlorhydris the evil witch had switched Cupid's love arrows with her own black-heart arrows that would infect its target with hate. But also on that day Sassette discovered that the witch's true love Manfred the Magnificent was frozen in stone by her rival Drusilla out of jealousy, and thus helped free her true love so that they could be reunited, though unfortunately the wizard got pierced by the black-heart arrows, which thus filled his heart with hate towards Chlorhydris.

Empath: The Luckiest Smurf stories
According to the story "The Prisoner Of Stone" in the EMPATH: The Luckiest Smurf story series, Smurfy Friendship Day is considered the birthday of the Smurf Village itself, when the various Smurf clans had joined together in one place to form the village. It is also the birthday of Cupid, who celebrates the day with his normal work of spreading love and joy through his love arrows.