On-duty radiologists should keep in mind some peculiar circumstances leading to intraperitoneale bladder rupture without fracture of pelvic bones. It is thus possible to identify the classical pattern of dog's ears topping the bladder, on the abdomen plain film, and the diagnosis may be confirmed by intravenous urography. An illustration is given by the reported case: a young man, after drinking too much, received a kick into the lap, followed by a severe pain and total urinary retention with a flat bladder.