The term has etymological roots in the basketball parlance that describes an attempt to score in the crowded and highly contested area directly under and immediately adjacent to the raised hoop on a basketball court, or "painted" area. Shot attempts in this area are traditionally only successful when made with a strong conviction to score, skill, overpowering strength, or a combination thereof (i.d. "going hard").
Bob: What happened bro??!!
J: I totally went Hard In The Paint with Rebekah! It was by far the slickest ride I've ever took in the Gentlemen's Pleasure Garden!