domain SlouchyBeanie.com

I've seen these terms used recently in the fashion industry.

boyfriendjacket.com
boyfriendjackets.com

I have no idea of the value, and the fashion industry is currently in a worldwide slump, so suggest you hang on to those two for now, along with the oversized pants domains.

They are good generic keyword names.

Indeed, OversizedPants is a good name. It's an exact match, but also looks like a catchy and organic domain name, even brandable. Definitely stick to it.
G-Nesis could be good, but the hyphen in brandable won't work...

Favourite of the bunch: Probably "oversized pants" ...low / mid hundreds

(In my opinion)