There was also a similar episode on Married with
Children. Al Bundy can't get on this sports trivia show
even though he knew every answer during the tryout
because he isn't good looking enough. So, he gets Kelly
on the show instead. She of course has a very
limited amount of knowledge that she can hold, but he
manages to cram in every piece of sports knowledge he
knows, while she slowly forgets everything else until
she is "full" and can't learn another fact without
forgetting a previous one. Right at the beginning of the
game, the host tells her how to use the buzzer, and Al
realizes that it must have displaced one piece of sports
knowledge, but he hopes it won't matter. She wins the game,
and decides to go for the $10,000 (I think) grand
prize question, which is "What quarterback holds a high
school football record for throwing 4 touchdowns for
Polk High?". The answer is her father Al Bundy, but
that is the piece of knowledge that was dislodged. She
ends up losing everything. That sort of fulfills the
"losing it all on the last question" part of the original
post.
Steve Lawrie, who is quite embarrassed at how well he
remembers this ;-)