We design the first practical adversarial attacks against object detectors in realistic situations: the printed adversarial examples (AEs) placed with different angles and distances, could hide (Hiding attack) or ‘make up’(Appearing attack) an object to deceive object detectors. We implemented our attack against two white-box object detectors (YOLO V3 and Faster RCNN) and four black-box object detectors (Faster RCNN/YOLO V3, Mask RCNN, RFCN and SSD).