"Kink" is a song produced by Infected Mushroom and Zedd in 2011. In 2012 Gaga bought the copyright of this song and used it in "Aura" instrumental production.
Background
The song was played several times during Infected Mushroom performances between 2011 and 2012. The duo has stated about buying ownership by Gaga: "She came into Zedd's studio, her producer, while he was working on our track. It was one of its first demos she immediately fell in love with. Zedd called us saying "There's a problem. Lady Gaga wants your song. We had some serious deliberation, we see ourselves as a band with a high artistic integrity and we avoid commercialization and doing cheap things such as Britney or Gaga. But suddenly there's a concrete offer on the table and saying "No" is a mistake, because it's a guaranteed lifelong pension. Each time the song is being played or sold, we get some pretty nice royalties. So we decided to give her the melody, as long as we are signed under our private names. We felt embarrassment for our fans. But she refused, she wanted "Infected Mushroom" to be credited. So, we decided to go for it thinking it won't make the cut or she'll eventually change her mind."