Occasionally described as a foreshortened view of a person with their arms outstretched.
Basically, the secret of this plate is to turn it. A good response is to say it looks like an animal hide (about the only reasonable response when held right side up), then turn it on its side and say it looks like a boat or surfaced submarine with reflection, and then turn it upside down and say it looks like a mushroom cloud, a pair of theater masks, or caricatures of men with long noses and goatees.