Questions & Answers about Oi, det var raskt.
Oi is an interjection. It expresses surprise, admiration, or a quick emotional reaction, similar to oh!, wow!, or whoa! in English.
The sentence still works without it:
Det var raskt.
Adding Oi makes it sound more natural and expressive when reacting to something that just happened.
Here, det does not refer to a specific noun. It refers more generally to the situation, what just happened, or that whole event.
Norwegian often uses det in this kind of general comment, much like English uses that or sometimes it:
- Det var bra.
- Det var rart.
- Det var raskt.
You would use den if you were referring back to a specific common-gender noun. In this sentence, you are not.