I’m tempted to scoff, but I was never up on stage in front of an audience, under bright lights and a TV camera when I was in high school - I guess the kid just had a brain-freeze.
https://www.youtube.com/watch?v=ZZhxHtM-12I
Here is another time when a contestant had a brain freeze...and what the puzzle’s answer was...ironic to say the least given what happened to the contestant.