I think this is the main source: peaceloveandnails.tumblr.com
For "Read Across America" day AKA Dr.Suess' birthday my older daughter and her teacher promised to paint their nails "Cat in the Hat" Style. Super easy and it turned out really cute...I did try to get her to do the "Cindy Lou Who" hair but she said no.
Using the toothpick we made the red large stripes on all the nails-except the thumb. For the thumb we painted small red lines, then outlined it in black nail polish.