Slow Burn is a popular trope where the characters of the main pairing start off not in a relationship and focuses on the slow development of a romantic or sexual pairing. They get to know each other deeply before engaging in any sort of sensual contact.
Man, don't cop that twenty sack from the south side, go get it from Keithen, he got that slow-burn..that sticky-icky! One hit and you gone have to put that out!