"In my head, I envisioned a nice scene where you see my hand slowly go out of frame," she told Conan. "But then when I showed up, the camera was mounted on the ceiling."
When she asked for direction, Maggie Carey's deadpan response was, "Masturbate. Like it says in the script."
In the romantic comedy, due out Friday, Plaza plays a high school senior who decides she needs more sexual experience before heading off to college.
2014: The Year in Music [PHOTOS]