To use these first You'll have to press [Alt]+[Backspace] and then enter one of the following codes:
Zap Me - Get 2,000 Electricity.
Brain Sick - Stronger enemies.
Color me stupid - Change troop colors (except for Vikki).
Ahoy Captian Dan - Get your Paratroopers at any location.
Fantastic Plastic - Get 5,000 Plastic.
Punch Line - Double the Dump Trucks Capacity.