Question: What is ... A SICK BURN!?!?

Yep, the Green Bay Packers QB was heckled during Final Jeopardy over that lousy NFC Championship playoff loss to Tom Brady ... and it was hilarious!!

Rodgers was a pretty solid guest host on Monday's show -- keeping a solid pace and offering some fun banter along the way. He crushed it.

But, the best moment of the show took place at the end ... when contestant Scott -- the reigning 2-day champion -- decided to have some fun at Aaron's expense during Final Jeopardy.

The category was Daytime TV Personalities -- but Scott realized he didn't know the material and couldn't win the game.

So, instead of scribbling down a legitimate guess ... he wrote on his monitor, "Who wanted to kick that field goal?!"

SICK BURN!!!

Aaron smiled, laughed and said, "That is a great question! It should be correct!"

Scott is referring to the bizarre call at the end of the NFC Championship game back in January ... where Packers coach Matt LaFleur opted to kick a field goal on 4th and Goal, despite being down 8 points with around 2 minutes remaining.

The Packers got the 3 points -- but Tom Brady and the Tampa Bay Bucs got the ball back and successfully ran out the clock, winning the game.

Most people -- including Aaron -- think Rodgers should've gotten a chance to score a TD on 4th down, followed by a 2 point conversion try. But hey, hindsight is 20/20 right?

Don't worry, Rodgers has a solid support system around him -- including his fiancee, Shailene Woodley, who raved about Aaron right before he made his hosting debut.

"This guy right here is super sexy, super attractive ... just shaved his neck this morning! Has a little man bun growing," she joked.

"This guy is hosting Jeopardy! tonight!"

So, why was Aaron selected to host? Rodgers actually won "Celebrity Jeopardy" back in 2015 ... and explained in his opening comments that he wanted to honor the memory of the late, great Alex Trebek.