* It's a mishearing or misspelling. There might be a similar-sounding phrase in Indonesian.
* It's a regional dialect or slang. The phrase could be used in a specific region or community.
* It's a made-up phrase. It could be a fictional term used in a story or game.
To get a better understanding, please provide more context:
* Where did you hear this phrase?
* What was the context of the conversation?
* What is the general topic of the conversation?
With more information, I can help you figure out what "sarung banggi" might mean.