Buy Nickelodeon Mood Gak - Purple to Pink - Nickelodeon Mood Gak will totally Blow Your Mind! Mood Gak changes color in your hands and comes in 3 amazing mood changing colors. Just hold Gak in your hands, warm it up and then watch it Change Colors before your very eyes. Nickelodeon Gak is Back and it's new Super Stretch formula stretches Farther and Faster!