Dean Winchester: You come back.
Sam Winchester: Promise.
Dean Winchester: B*tch.
Sam Winchester: Jerk.
From Supernatural – Season 12 Episode 22: ‘Who We Are’ (12×22) | TV series produced by The CW
This quote dates back to the beginning of the series. It is their expression of fondness, hidden behind insults. Could be perceived as their version of “I love you. – I love you too.”