This scene was in the following scenario: Someone stole Lina's panties. In the course of the investigation of the thief, the following characters are involved: Fiona, the gym teacher (?), and finally Risa. Risa is found talking to a guy wearing a Red Maiden mask. Then, if you wait a bit, the guy becomes quite pushy, because Risa doesn't feel like being in the story anymore. If I'm not mistaken, you are also supported by Scott and Bobby (the one of the two who wears the sports outfit all the time). The latter gets an unpleasant punch in the stomach from the mask guy.
To finally get the scene you have to tell Lina that Risa was involved in the panty thefts.