(noun) A large shit, that when shat, feels like you are passing a 9-ball from your ass. A 9-ball takes an extraordinary amount of force to pass.
Common injuries that occur from dropping a 9-ball include but are not limited to: sphincter tears, busted blood vessels in the eyes, hernias, bloody nose, and in rare cases death.
GUY 1: "Hey man, where've ya been? Your wings are cold."
GUY 2: "I had to drop a 9-ball!"
GUY 1: "Well that explains the limp and the blood."