Help finding a story in a theater

[SgtFC]

I'm looking for a story I read a while ago that I want to read again. I can't remember the title but I remember a general theme. I believe it is in the Group Sex category. A college girl pretends to be a boy and has a crush on a boy. Meanwhile a girl has a crush on her. The sexual encounter occurs in the theater as a threesome with the main character and the boy hiding behind the theater curtain to keep up the deception with the second girl in the story. If this sounds familiar to anyone could you point me to a title or author.

Thanks.
SgtFC