Trick question; the one that is NOT a sissy is the girl third from the left. A Sissy will never forget to bring her tights. (5 Sissies and 1 GG)
Can't argue with logic like that!
I'm going with 2nd from the right. She just has a bit of an unsophisticated, "I'm just so glad to be among these hotties" expression on her face.
Interesting choice and sound reasoning!