In the Glee episode "Laryngitis", Puck sings his assignment song for the week alongside Mercedes.
In the episode, Puck and Mercedes are assigned to sing a duet for their Glee Club assignment. They decide to sing "Lean On Me" by Bill Withers, and their performance is well-received by the Glee Club and the audience. The performance is a memorable moment in the episode, and it helps to bring Puck and Mercedes closer together.