what could it be if i hear a "BOWLING BALL" rolling sound in the back or under?

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! This might be a dumb question, do you have a bowling ball in the trunk? If not, The "bowling ball" rolling sound you're hearing when hitting the brakes could indicate a problem with the brake system or rear suspension components. One possibility is worn or damaged brake pads, brake rotors, or brake calipers. The type of material that the pads are comprised of can cause them to become noisy as they wear. Additionally, check for any loose or worn suspension components, as they can also produce similar sounds. I suggest having the brake system inspected by a mechanic to ensure safe operation and prevent further damage. If you have any other questions feel free to call us at 877-913-1554! We'll gladly find you a certified RepairPal shop in your area!