The Magic Coloring Book
Super easy to do, and amazing! Erik Dobell demonstrates this trick during Impossibilities and it never fails to get a gasp from the audience.
The Magician shows his friend his new magic-themed coloring book and as they flip through the pages, the appear to be black and white. That's until you do a magical gesture and all the pages are instantly in color! Another magical gesture and all the pages are blank!
It's great for kids as a beginner magic trick, and even adults looking to have some fun with their students, co-workers, or family.