Alan was confounded when he caught a distracted Nick repeatedly glancing at his watch. Alan found this puzzling because mathematics was Nick's favorite subject, and he was usually very attentive in class. When the bell rang to signal lunchtime, Alan asked him if everything was fine. Nick replied in a low voice that he would reveal a secret to Alan later. He asked Alan to make an excuse if others noticed his absence and quietly slipped out of the class. Nick's furtive behavior mystified Alan, who wondered why his friend was being so secretive. Alan was lost in thought, trying to comprehend Nick's odd behavior, when a loud cheer startled him out of his reverie. Nick, along with a group of his classmates, stood in front of him holding up a sign that read "Vote for Alan." Alan, who was running for class president, was touched by their gesture. - What is the meaning of furtive, in this sentence?

please help me :)