How do you get big boy in chuzzle deluxe?

To get the "Big Boy" trophy, you must play an entire classic or speed game without popping any of the large (2 by 2) Chuzzles.
An easy way to do this is to play the speed challenge on fast speed, play one move to set the timer going, then wait until the locks cover the screen, therefore using a scramble. Do this until both scrambles are used and then with no scrambles left, play until a large Chuzzle appears, and then wait until you lose. You should get the trophy.