Means burn the ganja, with a jamaican accent.
"Bun di ganja real hot."
Worthy of a bun.
When you decide that something ie an activity is not worth your time.
Comes from "bun that".
"My coursework needs to be 400 pages long"
"That's bun worthy"
Friends that you only spend time with to bun together (smoke cannabis) because smoking can be a social activity, but you don't interact in other situations and your conversations revolve around nothing but drugs.
After I got sober, I realised most of my circle were just bunning friends and not real ones