Meaning
What does Smile, Sweet, Sister mean?
Origin
What's the origin of Smile, Sweet, Sister?
The Blend S anime adaptation ran between October and December 2017, with the intro segment featuring the main characters saying “Smile, sweet, sister, sadistic”.
Remixes and parodies immediately started appearing online, with an early example dating back to October 12th, 2017, when YouTube user BlueEyes uploaded a video with the title “S” stands for? mixing the intro with a scene from Attack on Titan.
Spread & Usage
How did Smile, Sweet, Sister spread?
Over the years, countless parodies of “Smile, sweet, sister” were shared on the web, referencing other anime, like JoJo’s Bizarre Adventure, as well as Shrek and Somebody Toucha My Spaghet.

External resources
- Tvtropes.org – Manga / Blend-S
- Reddit – r/Warthunder