squinting

you can see in this picture that there is a distinct difference in the faces. here are some possible explanations as to why rachel and emily are squinting?

-is there a sand storm going on?
-did someone break wind?
-are they not use to seeing the sun out?
-doing some sort of jean impression?
-rachel hinting to all that she does not want to go to moe's for lunch but wants Ramen Ichiban
-just watched zoolander?
-trying to cover up the fact that their eyes are bloodshot.