I can't remember if I watched or read this scene, so I can't narrow it down much, sorry.

There was a scene in which a young girl is approached by a flasher. When he opens his jacket, instead of acting shocked she becomes critical. She looks for a moment and makes some sort of comment to humiliate him. Maybe something like, "Is that all there is?"

I believe someone had coached her to say this, and that she later told them that she did it and it worked.

I want to say that this is a mostly female work, maybe sort of cutesy, like Lucky Star or Azumanga Daioh.

That's a scene from Bokura wa Minna Kawaisou.

There's a similar scene in Family Complex too.