Why is a man hole cover round?
Anónimo
There are a few answers that would qualify as "correct", but I suspect this question won't be making the rounds much longer as this is becoming the stereotypical case example question which is meant to "see how you think". A circular manhole cover can never fall into the hole, as a square cover could by turning it on a diagonal, for example. Also, a worker can easily roll the cover without every having to lift it.