The Song In It's Always Sunny In Philadelphia S16E4 That References A Classic Philly-Set Sports Movie

Philadelphia sports fans never let an obstacle get in their way, be it the slick sheen of a freshly greased pole or desperate pleas that they stop throwing batteries. Unsurprisingly, this sort of unhinged passion has been explored extensively in "It's Always Sunny in Philadelphia" in episodes like "The Gang Gets Invincible," "The World Series Defense," and "Mac's Big Break."

In the Season 16 episode "Frank vs Russia," the gang explores the rough-and-tumble world of competitive chess. The episode pits Frank against a Russian champion, recalling the Cold War-era battles that manifested on the chessboard. "It's Always Sunny" brings a modern flair to the proceedings, alluding to a recent cheating scandal that would make Freud blush. 

As Frank cruises to an uncomfortable victory, "Burning Heart" by Survivor comes to a crescendo in the background. The track is best known for its inclusion in the "Rocky IV" soundtrack, and it's used here to ridiculous effect as Frank writhes on the floor in discomfort. Jimi Jamison's voice tears through the chugging groove, singing about Frank and Rocky Balboa in tandem: "Though his body says stop, his spirit cries, 'Never!'" 

It's hard to imagine a Philadelphia-set series not paying homage to "Rocky," and throughout the lengthy tenure of "It's Always Sunny in Philadelphia," there have been several references to the boxing franchise. Another famed "Rocky" anthem, "Eye of the Tiger," was even included in the Super Bowl episode "The Gang Wins the Big Game."

The "It's Always Sunny" gang seems to have a unique affection for "Rocky IV," based on their fixation with Dolph Lundgren, whose breakout role was the icy Soviet boxer Ivan Drago in that film. In Season 5, the gang unilaterally proclaims him "the most underrated actor of all time" and casts him in their fictional film about a crime-sniffing scientist. In Season 15, the Swedish action star even cameos as John Thundergun. 

In a decade full of them, "Rocky IV" is among the most heavy-handed Cold War allegories to grace the screen. Just look at the famed training montage, which contrasts Rocky's workout regiment (earthy, ax-wielding, bootstrap-pulling) against Drago's mechanized, steroid-filled training. It's enough to make you burst out a verse of "Rock Flag and Eagle."

Survivor's "Burning Heart" is just as subtle, with lyrics like "Two worlds collide, rival nations" and "Is it East vs West or man against man?" It's an appropriately dramatic accompaniment to Frank's battle against Russia, with Frank acting as some combination of Bobby Fischer and Rocky himself — even if Frank didn't single-handedly end the Cold War.