Budget Birthday Cake

I was inspired to make this Transformers (Bumblebee) colored cake for my son's 4th bday because he loves Bumblebee. I used boxed butter recipe cake mix and added yellow and red food coloring to white icing. This made the school-bus yellow color. I used black gel icing to write a message on the cake for my son. No special pan is needed. It is not fancy but made him happy. We did this cake on a rainy birthday while dad was deployed.