Unlike what you or your friends may have experienced in high school or college baseball, independent pro baseball team occasionally need to do unique things to survive. One of these is to differentiate itself and get local media in order to increase the odds of local fans buying tickets to every home game.
College and high school baseball programs often are subsidized partially by the school or alumni. Independent pro baseball teams have no such options, so unique things get booked even if they are unconventional.
Here is one thing you may experience either as a part of multi-day independent baseball team tryouts and/or during spring training: playing against prisoners in a state prison.
The San Rafael Pacifics (part of the newly-formed 2013 Pacific Association) played at San Quentin state prison in California. Here is the recap: