We have quite a few souvenir mugs, some from the kids' universities, and many from Christmas markets.
I don't know if it's the same on Christmas markets in the UK but if you buy cocoa, punch or mulled wine in Germany, you pay a deposit on the mug. You get it refunded on return, but we have often kept them. It is actually not quite legal but some of them have not only "Weihnachtsmarkt (Name of town) " on them, with a picture of the town's main landmark or logo, but also the year!
We have Heidelberg, Ulm, Bonn, Mannheim, Speyer, Augsburg.
None are singled out for a particular drink or time of day, though, or even a particular person.