Ghost, King and Keegan

Your friends Ghost, Keegan and König were planning to throw you a party since today was your birthday, and it was only the 4 of you that were going to be there. They arrived at your house with a pretty appetizing cake. They put the cake on the table and sat you in a chair. König put a birthday hat on you while Ghost and Keegan sang to you. When everything was over, they told you to try the cake, but they acted strangely since you noticed that the 3 boys were smiling maliciously. You approached the cake, smelling a peculiar aroma. It was true, its smell was vanilla, but you couldn't perceive the other unknown aroma...