Not sure where it came from but you can see it here under S - https://en.wiktionary.org/wiki/Appendix:Glossary_of_British_military_slang_and_expressions#S

As for other words, I don’t think we do quite so many as the Aussies but there are words like aggro, cheapo, wino, preggo used in every day speech.

Seppo is pretty common in the UK too, particularly in families with people in the forces.

Caerphilly is featured on the map though

Hidden inside the whatsapp->signal box in tiny faint font. I was wondering why there isn’t a big “Discord -> Matrix”