Proof that “sit down” is pidginized in Northern Chinook Jargon
An extremely frequent word in the Northern Dialect of Chinook Jargon is from English “sit down”…
This word /sit dawn/ usually conveys ‘being sitting’, or ‘sit down’ from a standing position — all as in English itself.

Image credit: Vatican News
But if we need proof that it’s become independent of English when it’s used in Jargon, there’s this excellent Bible passage:
“Tanas man, naika wawa kopa maika
‘ “Young man, I tell you,’Tlus maika mituit, pi ukuk iaka mimlus iaka sit
‘ “Stand up”, and that dead one sat’dawn…
‘up…’
— Kamloops Wawa #44 (Sept. 18, 1892), page 46
Here, sit dawn means ‘sat up’!
This shows how the verb’s core meaning in Chinuk Wawa is very generic, the same as simple ‘sit’ in English.
That is, sit dawn expresses all positions and changes of positions that have to do with the upper half of your body being vertical.
This difference from how the word is used in the language it came from is a diagnostic of pidginization of the English expression “sit down”.
Seeing as how most Northern Chinook Jargon speakers in 1892 didn’t speak English, this is no surprise.
