“That Was a Ripper” Means It Was Excellent

In informal Australian English, a ripper is an excellent person or thing. “That was a ripper” does not describe someone who tears something; it means the thing was excellent. It is more enthusiastic and colloquial than “good”, so it suits conversation with friends or a relaxed workplace, but not a formal report.

After a match decided in the final minute, you might say: A: How was the match? B: A ripper. It went down to the last minute. The article matters because ripper is a countable noun. If you only want to say that something was reasonably good, “It was good” is more natural.

https://dictionary.cambridge.org/us/dictionary/english/ripper