The term "Beuteltier" is regionally used as a minor insult, but I'm fairly certain that has nothing to do with what you've seen in an opera. :p

Where I'm from there are a lot of walnut trees growing all over the place at the sides of roads. In fall, when the nuts are ripe and start dropping, you can see a lot of people running around collecting them. They'll often bring sticks and stuff do beat nuts out of the trees, too. This practice while very popular by many is somewhat frowned upon by others since a) technically they're stealing (those trees, even if publicly accessible still belong to someone) and b) they sometimes create traffic hazards by having their eyes on the ground or in the trees, rather than on the road they're running around next to. Hence, those people are sometimes derogatorily called "Beuteltier", in reference to the often rather large bags of nuts they're carrying. (I know this doesn't really make any sense since a real Beuteltier doesn't use it's Beutel to carry food, but bear with me here, I didn't invent this usage.)