Bonch Share definition Flag Human Perineum, male or female. It's close to your heini and on girls it's tiny; ass side of ball-town, ball side of ass-berg. My bonch itches. I will bonch-shive you with a fork. Bonch by Cheryl Jordan, Justin Croft, Jessielizabeth Lyman December 28, 2005 Get the Bonch mug.