Pennies (pinnies) are mesh colored vests that are sometimes worn over jerseys when the two teams colors are too close to differentiate. You can switch the team color for the game then switch it back afterwards for future games.
You can do the color switch from the Team page at any time. You can also do it when you are importing a game you will be scoring soon.
From the game import page:
Note that games which are ready so 'Score' also have a right chevron on the right side of the screen. This is to indicate that you can change some of the team settings. Select a 'Score' game by touching anywhere aside from the 'Score' button.
Here you can change the team color to match the correct color for the game. Be sure to change the right color (Home/Away) or simply change both to the same color. Select the color to change it.
Color changes are only on the iPad and do not transfer back to Sport Ngin. The color change affect all games on the device for the team so you will want to reset the color after the game. You can do so in the same game list where you changed it initially or you can change it on the Team page in the app.
Either change affects the team in all games on the iPad.