Sentences with On The Sly

The spy gathered information on the sly, always staying undercover.

The artist added a hidden signature on the sly, a subtle mark only art experts could find.

On the sly, he altered the experiment's results to test the team's attention to detail.

The spy communicated with his handler on the sly to avoid detection.

The spy exchanged information on the sly with his contact in the dark alley.

The thieves entered the museum on the sly, avoiding security cameras.