What is a double belly buster?

Question

I heard this term while playing poker live, it skipped my mind back then but now i'm wondering what it means.

Answer 1

It's a term for a double gut-shot straight draw. For example:

Hero - 6H, 7H

Board - 3D, 5C, 9S

Hero would need to hit either a 4 or an 8 to have the nut straight.