Location: Miami
Level: Hide and Sea
The description should give you a good clue as to what you need to do. You need to find the basketball area, and drop something through the hoop. Doesn't have to be a basketball though. I threw a gate into it and it popped.
Load up the level and bring up your map. The flag you need to capture in the top right of the map is where you need to go. You should easily find the basketball area in the alcove by this. What you need to do is make sure your rioters have picked up junk to throw, then stand just in front of the flag pole and press RT when the red aiming reticle is over the basketball hoop. It may take a few attempts, but you will get it within a few attempts.
Let me know if the guide needs any adjustment.