Just for fun - don't want to upset your wife with beer stains on the table - use a beer coaster! 
 
4 inch in diameter work for any kind of beer glass. Number of designs to choose from:
Wehrmacht veteran drawing
Wehrmacht officer drinking beer
Adolf Hitler (2 sketches to choose from)
NSDAP badge
SS logo
Tiger tank pencil and color sketch
Royal Enfield motorcycle (ok, not German, I know. I have a weakness for that classic design)
 
Coasters are made of thick cardboard the graphics is vinyl laminated on top which will make them water (beer) resistant.