Immediately after finishing the mission "Trespass" for Phil Bell, head back down into the Sprunk factory. Go to the place where you first jumped out onto the roof. There will now be windows there. Shoot them out and you will get a series of messages that say, "Okay, that's it! You're done!", "Okay, let's bounce!", and "Pleeeeeease leeeeeeave!". After you shoot out the windows, you can also turn and shoot at the boards on the windows directly opposite them to continue the messages.