Shoot Arrows at Pac-Man
After you complete chapter 4 and learn how to draw the arrow gesture, you can fire arrows at pac-man in the sketchbook. Simply draw the arrow facing at pac-man and fire. When it goes past him, he'll lean back a little and scream "wa wa wa."
Bonus Gestures
Complete the following chapters to unlock the corresponding gesture:
Arrow: Chapter 4
Bomb: Chapter 8
Hidden Gesture: Rain Cloud
You can only do this gesture in the sketch book mode, which you can access in the Gallery. To perform this gesture, you need to draw a cloud. Just draw a circle using a series of "curly" motions. If you succeeded the lines that you scribbled will turn dark blue, and rain will start to pour out of the figure.
Hidden Gesture: Snake
In Sketch Book Mode, you can draw a snake by writing the letters "mw" as one continuous lines.