If you're looking for a free place to do your workouts, the NYC subway is one of the best places to test your strength and ability to impress (or piss off) your fellow subway riders. This is absolutely free, although, I can't promise that you won't be served with a ticket.
But hey, gyms can get boring, and the subway has a sturdy pole.
Subway Pull Ups
How many can you do?
Hope you're carrying hand sanitizer...
Ultimate test for balance and stability.
Get it, get it.
More Pole Dancing...
How do you even do that?!
Subway Seat Pushup
The Turnstile Hop
Here's a video of how creative you can get at the subway.
And you should probably really shouldn't do these exercises on the subway, but I ain't yo' mama.