Any leads on a metal mug that might fit in a pocket?
A sierra cup would fit in a large coat pocket. This one is from Evernew and is available on eBay. It's a bit pricy at $26, but you could get a SS one for $5.
These are terrific cups. I have several of the titanium Evernews that REI used to sell - I use them for my dog's watering cup on hikes/walks and on the road. In that way we always at least have a metal "pot" with us.
They are very durable and super lightweight.
The stainless versions are still pretty light and very compact and are what I've put in some survival kits that I've built and given away.