This is super simple. 

s t e p - o n e :

Open your text box in Pixlr Editor. Type in anything - use any font and any color. Once this is completed you will not be able to go back and change this unless you start over.

s t e p - t w o :

Right click on the layer and select "Rasterize layer". This will make it editable.

s t e p - t h r e e :

Go up to "Edit" and select "Free distort..."

s t e p - f o u r :

Lastly, move the transform boxes until they look something like this :

If you wanted it to go from little to big, just switch it around and you're done!