Yoseob is a member of an all boy-group (k-pop) in Korea, called BEAST/B2ST.
His full name is Yang Yoseob.
He's known as the "Visual Maknae'' of the group, though he's not the youngest, which is what 'maknae' means. Another one of his nicknames is the "God of Food".
He's known for his cuteness/Aegyo.
Abbreviation for: you only say YOLO once
Because of how incredibly gay the acronym YOLO is, you're only allowed to say it once in your life. Yosyo however can be said as much as you like. It's a thing.
Guy 1: Dude did you end up setting off those fireworks in your bathroom last night??