Eulerian beer

At mathlog: Jever Bierdeckel-Mathematik und die Brücken von Kaliningrad. That is, "Jever coaster mathematics and the bridges of Konigsberg." (Why this funny translation? Because you haven't heard of the bridges of Kaliningrad, even though that's what the city is called now.)

It includes a solution to the general problem of identifying graphs with Eulerian tours. In English, in the form of a poem.

And what do coasters have to do with this? Jever is a beer, and the problem of finding an Eulerian tour is on a coaster they distribute (in German).

Edit, 1:28 pm: In the comments, Wing says that he thought the post would be about Euler beer. Apparently there is a beer named Euler. Someone's auctioning off a coaster on ebay.