What is "baby daddy"

n. (context slang US English) Father of child in common, particularly unmarried.

Baby Daddy is an American sitcom created by Dan Berendsen that premiered on June 20, 2012. The series follows Ben, a man in his twenties, who gets the surprise of his life when a one-night stand leaves his baby at his doorstep. Ben decides to raise his little girl with the help of his brother, Danny, his two close friends, Riley and Tucker, and his mother, Bonnie.