If someone opened my beer with this Klein Bottle opener, I'd probably yelp in fear. It looks so alien and just plain weird that I can't believe it actually works.
Here's what Bathsheba Sculpture, the company behind the Klein Bottle opener has to say:
The problem of beer: That it is within a 'bottle', i.e. a boundaryless compact 2-manifold homeomorphic to the sphere. Since beer bottles are not (usually) pathological or "wild" spheres, but smooth manifolds, they separate 3-space into two non-communicating regions: inside, containing beer, and outside, containing you. This state must not remain.
A proposed solution: Clearly the elegant course is to introduce a non-orientable manifold, which has one side and does not divide 3-space. When juxtaposed with the beer-bounding manifold described above, it acts to disrupt the continuity thereof, cancelling the outdated paradigm of distinction between interior and exterior. This enables the desired interaction between beer and self.