The multiverse-traveling duo Rick and Morty have been on a number of wild and wacky adventures throughout their sci-fi careers, though none have been as strange as the time they had to sing their original song "Get Schwifty" to a giant celestial head to save the world. While the song seemed like a musical mess of lyrical nonsense that Rick just made up off the top of his head, one past adventure described in a Rick and Morty comic book explains why "Get Schwifty" was actually the perfect, and perhaps the only song for the situation.
In Rick and Morty Presents: The Flesh Curtains #1 by Lilah Sturges and CJ Cannon, fans are given a glimpse at Rick’s past before the events of the Adult Swim series. In the comic, Rick, Bird Person, and Squanchy are in a band but their anti-establishment vibe is not well received by fans. So, in light of their failure in the music business, Rick does what he does best and invents a device perfect for their predicament.
In the comic, Rick creates a machine that scans the brainwaves of an individual and comes up with an original song that they are guaranteed to love. While using the device, Rick’s band becomes super famous across the cosmos as their music appeals to every individual who hears it. Knowing that Rick has access to this specific song-writing technology, it makes sense that he would know exactly what song to play for the "Show Me What You Got" heads in Rick and Morty season 2 episode 5. While "Get Schwifty" seemed random, it turned out to be the perfect song to play for the heads as it earned planet Earth a final spot in their intergalactic game show.
The way Rick’s song-writing device worked in Rick and Morty Presents: The Flesh Curtains was that it projects the perfect song for someone or a group of people into Rick’s head and he can just play it immediately without having to rehearse. Since Rick and Morty (and Ice-T) had plenty of lead time to come up with a song for the giant heads, Rick could have easily used this device to instantly learn what song he needed to play in order to ensure the survival of the planet.
Since Rick’s device works instantaneously, it's no wonder he and Ice-T were so relaxed before showtime. Ice-T is revealed to be an elder being of the cosmos so he just didn’t care about planet Earth in general, but Rick was relaxed because he used the brain-scanning songwriter machine to know exactly what the giant heads wanted to hear as well as knowing how to play it for them. Rick’s past perfectly explains why "Get Schwifty" was the perfect song to play for the giant heads in the season 2 episode of Rick and Morty, and as always, it was because of Rick’s unparalleled genius.