Get wide, cartoony eyes.

Here’s my beginning image:.

Now I am going to Image >> Liquify and choose the “Bloat” option from the menu on the left:

If you look at the other side, there are your brush options. All you need to really adjust is the size of the brush and perhaps “brush”. Brush controls the intensity of the liquify effect and the size, obviously, determines the size. Choose a brush size the same size at the eyes and I suggest, trying out the “brush” options. Anyway, apply the brush and you will see the etes widen.

My final image:

But you can make it more dramatic if you like. Liquify is also capable of narrowing things as well. Choose the pucker tool and check it out.