Whenever somebody serves a dollop of opinion into a conversation, argument, or situation that doesn’t really concern them:
It can also feel closer in meaning to meddle:
✅ Fun and visual!
✅ Informal, but not rude-rude.
✅ Can sound jokey or annoyed depending on your tone.
No faltó quien metiera [la cuchara] - what a curious little expression in and of itself this is! I'm guessing it must trigger the subjuntivo, eh?