Dean likes beer. He also likes coffee. So when Castiel made him one, he fainted. When he came to, Cas was edging towards him asking if he was alright. He looked so adorable Dean fainted again. Castiel made sure never to make Dean coffee again. Dean was sad about this and just asked Sam to make his coffees. Sam's coffees were nice but not as nice as Castiel's.
The end
Dean is hoping to receive some coffee from Cas on his birthday.