http://www.simpsonizeme.com/#1.

This is the Simpsonsize website. Click on the button to begin
2.

Find a decent quality potrait of yourself or it might not work. (Read the instructions on the website for more details)
3.

Alter the options to which suits you the most
4.

You should see your picture in the middle with the "Simpsonise" button on it. Click it, and Kang and Kodos will appear, starting the transformation
5.

Alter and fiddle around till you are happy with your look
This is one of me i did earlier.

Now let's see you