Its really not so much "smart" people, as well read people or something. I mean, not everyone who is smart knows what a ****** of crows is. (also, those are Ravens by the way) But either way, this joke makes no sense in any language but English, and I know plenty of people who are very intelligent, but probably wouldn't get this joke due to a limited vocabulary. Large vocabulary does not equal intelligence, even if the two are frequently associated with each other.