Dean
Cutiepie. You were like his pie and you were cute.

Sam
Shortstuff. You were short compare to him. But, yet again, everyone is short compared to him.

Castiel
Beautiful. Pretty self explanatory.

Gabriel
Sweetie. You were like a sweet to him. But, the sweetest sweet. The type of sweet he got to keep forever.

Lucifer
Honey. Lucifer stays classic.

Crowley
My queen. You are the queen of Hell.

Balthazar
Kitten. You had to take some photos of a lion who grew very fond of you. Balthazar thought you had some sort of feline traits in you after that thus leading to your nickname.