Green’s Dictionary of Slang

(Aus.) a flannelette shirt.

2005		L. Redhead Rubdown [ebook] His usual crumpled flannie had been replaced by a black jacket over a [...] sweater.
2010		L. Redhead Thrill City [ebook] I recalled the word red flannelette shirt [...] There were a lot of flannies in the world, and it could have been a coincidence, but..