I have seen this one from eBay.
https://www.ebay.com/itm/RC449-Mens-String-Thong-Contoured-Pouch-Small-Triangle-Back-Star-Stripes-Flag/183175363340
Think it's neat that there are two design choices for the mini-triangle in the back.
I haven't bought anything from them yet, though, so can't speak to the quality. They seem to have cool stuff at really good prices, so I am going to do more research. It's hard to tell the design and quality from those pictures only...