The bonus he received in addition to his salary was pure 'gravy'.
They're trying to get on board the 'gravy train'.
a 'gravy' boat [=a container for serving gravy]
(..) take deep breaths. In and out. Deep breath in... and out. In and out. - It's troll's favorite food! - Princess! - No, Daddy! No, Daddy! - Roasted princess with paprika and gravy! - No! No, Daddy. No, Daddy. Whoa, hey! Hey. You all right? - What's going on? - Whoa. - What happened? What happened? (..)2016 TvShow: Stranger Things Title: Chapter Eight: The Upside Down Season: 1 Episode 8