Pete LaCock hit the first pitch he ever saw from legendary pitcher Bob Gibson for a grand-slam homerun, powering a come-from-behind Cubs win over the Cardinals. It turned out to be the last pitch of Gibson’s career when days later he decided to retire. Legend has it that Gibson faced LaCock in an Old Timers game years later and got a measure of payback, though an interview with Gibson about his views on Old Timers games may cast some doubt. On the other hand, you might be persuaded by this 2001 interview with LaCock where he gives his version of what happened.