In October 1999, for the final annual football kick Sunday strip, Lucy gives little brother Rerun the opportunity to hold the football for Charlie Brown and goes inside. We see Charlie approach the kick and then the panel switches to Rerun inside with Lucy. She asks "What happened? Did you pull the ball away? Did he kick it? What happened?" What did Rerun reply, aptly ending the theme that ran annually for over 40 years?
"You'll never know." or similar.