Get him one big box. In it, you give him one smaller box containing the specified number of Transformers toys, and another box containing two of these:
Then hide the remaining two Transformers in the fridge or some other box-shaped object.
You can't just give your family the stuff they want for birthdays and Christmas. You gotta do stuff like swap out the DVD case for Punch Out! with one of the recipient's daughters' Barbie movies. Oh, did their eyes ever get big when they saw that their Daddy got Barbie for his birthday. "Daddy! Let's go watch it!" they exclaimed.