The phrase comes from everyday German youth slang, where Digga is a casual term for a mate or dude, similar to bro in English. Weiss ich nich is the relaxed, shortened form of I do not know, so the whole line works as an instant verbal shrug. Clips built around short slang phrases like this spread easily through group chats and short videos because they need no setup or translation for German speaking audiences. It stays popular as a reusable answer to almost any question where honesty and indifference are funnier than an explanation.