Totally agree.
A shockingly small number of candidates I've interviewed have heard of fizzbuzz. The first time I mentioned it to someone, I assumed they already knew it and would just chuckle and crank it out. However, that's actually kind of rare.
When I do talk to a candidate and get that "knowing grin", my estimation of them jumps up a couple of notches. It seems to actually mean something outside of coder forums.
The real downer is how dismaying it as that candidates clearly have never prepared. How could they have done any research ahead of time and NOT seen fizzbuzz?