His confidence in saying “dick” was more rooted in the word being known slang for detectives, while not so much considering any words that come from tree names. with or without referring to Rogers’ guess, he chose to say, “I know nothing about a dick tree, but there is a gum tree.”
For those who didn’t watch the clip, or weren’t able to, Alex Trebek read out a clue for the category “Starts Or Ends With A Tree,” which had the answer “Slang for a detective.”
And it’s not even clear from his own reaction if he realized the hilariousness of his admission.
Austin Rogers rang in first, but clearly without the correct question in mind.