Sing for Your Supper and...Exercise for Your Subway Ticket?

Not everyone is capable of doing squats, especially if you have bad knees, but for those who can, it looks a if this subway ticket machine that was set up to accept 30 squats in exchange for a subway ticket turned out to be fun. (I'm sure there were other machines for those who preferred or needed the traditional approach).

I'm having fun trying to imagine other types of exercises they could have asked for at other machines. Jumping jacks?