Challenge him or her to a Tag-Off...
A simple game of chance. Once a Tag-off has been made, each person must press a button
to reveal a subway line. If your display reveals a subway line that stops at that station, you win.
...or a game of skill.
Press the button as fast as possible to make your train arrive in the station
The first to arrive wins, and their MTAG is displayed.
You may have noticed that some MTAGS are personalized artwork and not just photos
How did they do that? (Click on MTAG Tab on the linked page)