I got the "manhole cover is round" problem at a interview. I'd already heard it before and admitted so and proceeded to give a number of reasons why it was round. They were still impressed.
Except that question in particular is a fairly silly one. A satirical rendition exists that illustrates why, and happens to have been discussed long ago on HN (https://news.ycombinator.com/item?id=569897) but apparently the original article has moved (https://sellsbrothers.com/12395).
https://web.archive.org/web/20070810204407/http://www.sellsb...
Instead they should have asked: design a manhole such that these constraints are satisfied.