Hi Anastasia,
Welcome to Digicamhelp. You're right, that is strange.
A whole lot of factors including camera settings, angle the shot was taken, ambient lighting, etc. played into how the eyes appear in the photo. I have a theory, though, about those eyes.
Most digital cameras have a red-eye reduction mode which emits a series of rapid pre-flashes before the full flash goes off. The pre-flashes help reduce the reflection in a subject's eyes by causing a subject's pupils to contract. So if you use red-eye reduction flash mode, your friend's eyes contracted, adding to the look in that picture.
I've taken quite a few photos where the flash has made the subject's eyes look pretty strange. I'm not sure the "cat eye" look can be
intentionally repeated again.
Related reading:Prevention and removal of red-eyehttp://www.digicamhelp.com/digital-photography-tips/red-eye-removal.htm