O Button (blood Type) on Snapchat

What it signals here

friend system usage

Not tied to Snapchat's friend system directly, but may appear in snaps as a decorative letter or blood type identifier in personal health snaps.

streak use

Rarely used in streaks; its blocky appearance makes it occasionally fun to spell short words in streak messages.

story meaning

May appear in story text overlays for aesthetic letter art or blood type personality quiz stories.

snap context

Used casually in snaps as a bold letter O for emphasis or humor, or in the context of anime/K-pop fan identity posts.

See it elsewhere