The girls were only so accurate with their prediction because Fang Fei was being too obvious about it. That man… this nickname represented the unique place the person occupied within Miss Fang's heart, and regardless of whether it was her nemesis or her crush, the person behind that number was unique from everyone else to Miss Fang.
The girls predicted that it was her crush because when they'd joked about it with her, she hadn't denied it. However, now, it was a lazy yet aloof female voice who answered the call. To be able to use such an easy tone to answer the call meant that the person was either the owner of the phone or someone who had a close relationship to the owner.
Based on Miss Fang's reaction, which was one of utter surprise, then the chance of it being the former was low. This meant that it had to be the latter.
Honestly, the group of girls around Miss Fang were at bit of a loss.