A baseball cap that is turned inside-out and backwards or sideways, worn by a fan, in anticipation of a possible batting rally by their chosen team during a game in which that team is trailing.
The most common type of rally cap is simply a baseball cap that has been turned inside-out (inverted) and worn forward or backwards. Other variations of the rally cap have seen the cap worn sideways (also sometimes inverted)-the point being that the wearing of the hat is noticeably different than its regular style. Rally caps usually appear as a trend beginning in the late innings of a game, from the seventh inning on and are most often sported by home team fans. Some fans have supplemented or replaced the rally cap with other superstitious items or practices, such as the rally monkey, rally chew and rally towel.
According to most sources, the true emergence of the rally cap occurred during the 1985 season with the New York Mets at Shea stadium.