This is a mobile app of famous Hot / Crazy Scale form How I Met Your Mother.
This app helps you rate girls.
The Hot/Crazy Scale is a graph used to display someone's hot-to-crazy ratio.
As Barney explains in How I Met Everyone Else, a person is allowed to be crazy, as long as they are equally hot. Ideally, you want your date to be above the diagonal line, indicating that they are hotter than they are crazy.
The diagonal line is known as the Vicky Mendoza Diagonal by Barney, after a girl he dated who jumped back and forth across the line by shaving her head, then losing ten pounds, then stabbing Barney with a fork and finally getting a boob job.