This is using the Gestalt principle where we are using positive and negative space. The negative space of the coffee cup is actually a person talking and the top of the coffee cup comes out to be a thought bubble.
Just smile and wave! Do the princess wave! In other news, if you know Jesus in your heart, you don't have to act like a princess b/c you are one. B/c your father is THE KING! So SMILE & WAVE, you princess, you!