How did he get the nickname Sweet pea?

Geogre Joes named him that

I know that much but why did he name him that is my question

If I remember the story right, Vince was over at George Jones house one night for dinner, and Vince pulled the chair out at the table for George's wife, and his wife said to Vince "oh you're such a sweetpea". So that's how Vince got the nickname "Sweetpea."

George sure hit the nail on the head when he called him Sweetpea too.