Sorry I missed this a couple of days ago, but it's been 25 years since
this happened (well, 25 years and 2 days now).
I was at that game. Play happened during a 5-5 game in the top of the 9th, after the Reds had just tied it up the inning before. My dad threw a styrofoam cup holder onto the field from the left center 2nd deck seats. Fun times all around.