Thanks for the interesting question.
The tradition/superstition where fans wear their caps inside out (and
often backwards as well) is commonly called the "rally cap". It is
intended to bring their team good luck when they are behind in the
score - so that they will "rally" and win the game.
Parts of the Uniform - Caps
Quote: "The baseball cap is the quintessential American hat. It is
seen not just on the ball field, but in the stands, on the streets and
even at the workplace. Today, as in the past, the baseball cap serves
many functions. It shades a player?s eyes from the sun during the day
and from artificial lights at night. It helps players and fans
distinguish members of one team from another. A cap?s distinctive
coloring and graphics help promote the team and make for an enticing
retail product. And how could a club mount a late-inning comeback
without displaying an inside-out ?rally cap??"
Rally Cap - definition
Quote: "In the late innings of a baseball game, when a team is down by
a couple runs, its players will often break out the rally caps. The
most common way is to turn the baseball cap inside out and wear it.
Occasionally athletic tape is used to bend the cap into weird shapes.
Must be done as a team or somebody just looks corny."
The tradition started in the 1986 World Series between the New York
Mets and the Boston Red Sox:
The Rally Cap Story
Quote: "The Rally Cap® was born during the 1986 World Series when the
New York Mets were playing the Boston Red Sox. The Mets were losing
Game Six and already down 3 games to 2 in the series; it seemed almost
certain that the Red Sox were going to be the 1986 World Series
Champs! In the 7th Inning of that game, something amazing happened;
the Mets all started wearing their caps inside out while sitting in
the dugout. Catching on, the fans also started to sport their caps
inside out and called it the 'Rally Cap®'."
A series surrounded in superstitions
Quote: "And how ?bout dem rally caps? Not unique to Boston, the rally
cap was actually invented when the New York Mets faced off with the
Sox in the 1986 World Series. As usual, the Sox were close to winning.
In fact, up three games to two, they would take the series if they won
game six. Then, during the seventh inning, all the Mets in the dugout
started wearing their caps inside out. The fans caught on and did the
same. Before anyone could say ?Bambino,? the New Yorkers took it back.
Then they took game seven too, for good measure."
The rally cap superstition is no longer isolated to baseball. Since
the "baseball cap" is ubiquitous these days, the rally cap can be seen
at pretty much any sporting event. It can even be seen outside of
sports altogether, when someone wants to change their bad luck.
Search Strategy (on Google):
* "baseball caps" "inside out"
* "rally cap" "inside out"
* "rally cap" history OR origin
* "rally cap" 1986 "World Series"
I hope this helps!