This reminds me of the first time somebody won the $1 million on Who Wants to Be A Millionaire, only a lot less money. That guy used a lifeline to call his family and tell them he was about to win the money, capturing the hearts of every viewer. This final Jeopardy contestant went a bit of a different route.

This guy didn't know the answer, and instead of making an educated guess, he went the comedic route. 

Obviously not knowing the answer, he just decided to make a joke which in a normal audience might get a chuckle but caused a Jeopardy audience to lose its hysterical mind.