It turns out Podrick knew one. More specifically, he knew “Jenny’s Song," a song plucked from the pages of George R.R. Martin's A Song of Ice and Fire books and one that connects to some of the biggest storylines on the show. The "Jenny" of the title is thought to be Jenny of Oldstones, who had an affair with the Mad King's brother Prince Duncan Targaryen and caused him to give up the throne for her.
What does that have to do with where we are now? As this helpful primer on Vanity Fair points out, the song is actually "tied to Rhaegar and Lyanna’s love, to Jon and Dany’s origin, to the Azor Ahai prophecy." (If you need a refresher on the Azor Ahai prophecy, we've got you covered.) In the book, the only line from "Jenny's Song" featured in the text is this one: "High in the halls of the kings who are gone, Jenny would dance with her ghosts.”
Of course, the version that we got from Pod went on quite a bit longer, featuring original lyrics and music by the show's composer Ramin Djawadi, and it allowed actor Daniel Portman -- yes, that really is him singing -- to really show off his vocal skills. "The ones who’d been gone for so very long/She couldn’t remember their names," he sings. "They spun her around on the damp cold stone/Spun away all her sorrow and pain/And she never wanted to leave/Never wanted to leave." The last line repeats as we see a montage of Sam and Gilly, Theon and Sansa, Grey Worm and Missandei, and a handful of other characters who might not survive the coming battle.