Plastic bag animal sculptures for subway gratings

An unknown artist fashions animals out of plastic bags and fastens them to subway gratings, and the hot air inflates them and makes them puff up and wiggle.

The story we heard at dinner tonight is that there's an artist who's been making these animals out of discarded plastic bags. He (or she) ties the bags to the ventilation grates above the subway lines so that when the subway rushes through underneath, the animal jumps up and springs to life.
Link (Thanks, Marilyn!)