Only one man in baseball history has hit two grand slams in one inning, and that man is Fernando Tatis. Fourteen years ago today, he took Chan Ho Park deep for both salamis. Here is the MLB.com video, which unfortunately isn't worked properly when embedded.
Know how I remembered this was the anniversary of the two grand slam inning? Tatis was kind enough to remind everyone:
Chan Ho...if you are reading this...i hope you are well...today is the day i blasted two grandslams off of you...i am very lucky to face you— Fernando Tatís (@FernandoTatis17) April 23, 2013
Poor Chan Ho Park. Not only was he left in to allow both grand slams, but he's still hearing about it on Twitter more than a decade later.