A boy you should not be associating with, or are supposed to hate, yet you do anyway.
(At a football game)
Kate: "Hey, see that cute guy on the other team? I wanna go talk to him!"
Shaniqua: "No Kate, we don't do that in this house. You don't need everybody else to hate another boyfrenemy of yours."
i.e. Boy from rival school, organization, outside your social circle, etc.