In the episode "The Route of All Evil," the "Futurama" gang tries to find good beer. In their search, they come across St. Pauli Exclusion Principle Girl beer. It's a reference to the German-brewed St. Pauli Girl beer, perhaps most well known for their logo featuring a blonde woman in traditional garb.
More importantly, it's a reference to the Pauli Exclusion Principle, a law of quantum physics first described by physicist Wolfgang Pauli (who was Austrian, not German) in 1925. The principle explains that particles with a certain kind of spin (an intrinsic property of quantum particles) can never occupy the same quantum state.
While the nature of quantum states and particle spin can be difficult to grasp, the results of the exclusion principle are easy to see. Without it, we wouldn't have different elements with different properties, like oxygen, copper, plutonium, hydrogen, carbon or anything else on the periodic table. Without elements, there wouldn't be much of anything in the universe. This is because the Pauli Exclusion Principle is what forces electrons into different energy levels, or shells, around the nucleus of an atom. Those different electron energy levels are what give elements different properties and allow them to interact and form new elements and chemical reactions. Thanks, St. Pauli Exclusion Principle Girl!