Cystic artery pseudoaneurysm (CAP) is a very rare complication of acute cholecystitis. The pathogenesis of CAP in the context of cholecystitis is unknown but is possibly related to the inflammatory process in the vicinity of the cystic artery, leading to weakness in the wall of the artery.Though CAP has been reported in the literature, our patient had a unique presentation in the presence of a cholecystostomy catheter in situ. There were no risk factors for CAP in our patient including usage of anticoagulants, trauma, or surgical procedures. Fortunately, the blood-stained fluid in the cholecystostomy catheter effluent alerted the clinical team to a possible vascular complication in the background of ongoing cholecystitis. This finding should serve as a warning sign to alert clinicians to the possibility of CAP-beware of rattling underfoot.