It is a tart-like pastry, hence the word Tart in its name. The "Pop" does not refer to popping out of the toatser - It was named Pop-Tart as a play on the "Pop-Art" craze at the time of its creation.
I haven't found the ninja yet but I am so close to finding him. All you have to do is get the black belt by playing the game next to jim's gym. quit after you win the first level and you will get it....