Wait till he brings out the evening’s libations stored in a Klein bottle.
The Mobius strip is often described as “one-sided,” for the obvious reason.
Martin Gardner wrote a story called “The No-Sided Professor” about a mathematician who perfect a series of paper folds that produces a no-sided object that promptly vanishes. Applying the procedure to himself with a set of yoga-like postures, he makes himself vanish. But he also got revenge on a rival by folding the poor man into the non-existent shape.
I first saw it in a book of math based science fiction stories called Fantasia Mathematica .