Lunch cooler

You might still find some of the retro Pilsner Urquell units they were selling a few months ago (no thermos, though).

 

Here is a nice high end one from Alaskan Brewing made by Filson.

 

To be honest, I try to keep my hobbies out of the workplace - there's always someone there who would see a beer logo and think that I (you) are always drunk, or there's some issue with alcohol that affects your work. I try to keep it simple.
That said, I have a nice growler cooler from Jack's Abby brewing, Fairly simple, rectangular one with their logo (of course, now I'm not seeing it on their website.)