When Benny Friedman sings
"Hustle Yossel move a muscle"
Is Yossel referring to anyone or is it just Marcus brothers poetry?
The song is a tribute to his uncle, Rabbi Gordon, who's voice you hear speaking in the song. "Mitoch meretz ubitachon chazak" is a response he received from the Rebbe, and when repeating it, he would often use the phrase, "hustle Yossel, move a muscle."