Gav'ot toH'va was a piece of Klingon opera. When Ezri Dax rescued Worf from the escape pod from the IKS Koraga he had been stranded in, Dax guessed he had been singing opera like Shevok'tah gish. Worf had been singing opera, but Gav'ot toH'va. (DS9 episode: "Penumbra")