Final answer:
Dwight sings 'The Sons of Molly Maguire' in S6E17 of 'The Office' to guilt Jim about returning from paternity leave.
Step-by-step explanation:
In Season 6, Episode 17 ("St. Patrick's Day") of The Office, Dwight Schrute sings 'The Sons of Molly Maguire' to guilt Jim Halpert about returning from his paternity leave. This song choice by Dwight is meant to suggest that Jim should prioritize his family commitments over his job, by referencing a historical group known for their dedication to worker's rights.