No. 1990.07.16 · Free Agency Era
Steve Lyons Drops His Pants
Steve Lyons beat out a bunt, slid into first, and unbuckled his pants on live television to shake the dirt out.

Steve Lyons, by then a Dodgers broadcaster, on April 20, 2013. This is not the July 16, 1990 game in which he dropped his pants.
Keith Allison, CC BY-SA 2.0, via Wikimedia Commons.
July 16, 1990, Tiger Stadium. Steve Lyons, the White Sox utility man whose nickname was Psycho, led off the fifth with a bunt single against Dan Petry and slid into the bag. While Petry argued with first baseman Cecil Fielder, Lyons felt the dirt in his uniform and did the thing a person does in a backyard: he unbuckled his pants to shake it out.
He got them to his knees, remembered the crowd and the broadcast, and hauled them back up. He was wearing sliding shorts. Nobody was hurt. The clip outlived almost everything else he did on a baseball field, which is its own small injustice and also the reason it is in the catalog. Lyons later became a broadcaster and told the story on himself, which is the decent version of this kind of moment.
It is here as a personality entry, not as a moral one. The sport has room for a man who forgot, for three seconds, that he was not alone.
Film
Lyons drops his pants
Steve Lyons pulls down his pants at first base after beating out a bunt.
Watch on MLB.comRelated entries

The Ball Comes Off Canseco's Head
Carlos Martinez flew to right at Cleveland Stadium. The ball ticked Jose Canseco's glove, hit him on the head, and bounced over the fence for a home run.
Texas Rangers · Cleveland Indians

Eddie Gaedel Walks
Bill Veeck sent 3-foot-7 Eddie Gaedel to the plate in a child's uniform. Gaedel walked on four pitches. The league voided the contract the next day.
St. Louis Browns · Detroit Tigers

Castillo Drops the Popup
The Mets led by a run with two outs in the ninth when Luis Castillo dropped Alex Rodriguez's popup, then threw to the wrong base.
New York Mets · New York Yankees