When you are out with your mate/s and have access to his/there car heres what you can do... Get something small or round (e.i: Sliced Cheese, Ripped up paper, soft balls, etc etc) but make sure it fits well enough in the Cars Air vents. Once you have the material or Food lol... Put it in the Air vent Iv got this picture from google, i am not advertising Also make sure you put some at the back of the dash board where the front window is. Then Face them up, turn on the aircon HIGH! and your set When he turns the car on he will be facing some cleaning... enjoy
an even better way to do it is open the door, and where that big black tubelar thing is on the inside part that connects to the car when the door closes, you can fit anything there, including the sock idea. Pour some powder, cheese, anything, it's all accessible, so it wont get stuck.