Key and Peele are in the Army now! I’d imagine that while your squad is out on a forced run, building endurance and powerful blisters, the call and response to the cadence of your feet must act as a mindless distraction from pain and exhaustion.
Movies depict sing-song rhymes about the girl back home, your best friend the gun, and general insults, none of which are particularly thought provoking for weary recruits on the move. The drill sergeant in this skit didn’t receive his copy of “Mindless rhymes For Running.” His mad rhymes are steeped in a reality where the rich stay home while the poor fight the wars.
He doesn’t know why, but he knows how to motivate his troops to make tracks!