"The problem that bothered them was this. Suppose the harried waiter cuts the pizza off-centre, but with all the edge-to-edge cuts crossing at a single point, and with the same angle between adjacent cuts. The off-centre cuts mean the slices will not all be the same size, so if two people take turns to take neighbouring slices, will they get equal shares by the time they have gone right round the pizza — and if not, who will get more?"
This is useful, of course, if you're familiar with the concept of "sharing" a pizza.
Chemist who falls in acid is absorbed in work.