I watched that match back in high school (his streak corresponded with my own academic bowl team's season), and "What is a hoe?" was my response, too.

I'd never heard that semantic sense of "rake" before, and felt somewhat scandalized that "hoe" would be a response on national television (while in high school, I felt great affinity toward the puritans).

I have known that from this: http://en.wikipedia.org/wiki/A_Rake%27s_Progress

Does anyone else think "hoe" is actually a valid answer there, though? It's hard to tell from Ken's facial expression whether he "purposefully answered incorrectly" or just found himself amused at the situation.

Hoe is not a valid answer because the other word you are looking for is "ho" which is a shortened form of "whore".

Rake, on the other hand, is a homonym.