Earbud.org has a very bizarre and slightly disturbing animated flash ear that opens their website. As I recall, when I was a young lad, Mr. Peanut (go here to see further weirdness) scared me in a similar way. Creepy Ears also have this quality.
But seriously, you had better follow Mr. EarBud's advice: We had far too many professional musicians, engineers and producers visit the lab who failed to hear the many sneaky, secret test tones that I have around here. We have had some very young ears in here too, and they failed to hear even a moderately loud 18 KHz tone, so it should be no surprise that none of the adults heard it, and most did not hear the TV horizontal oscillator frequency either. A large few heard very little above 10 KHz.
I think it's a dirty little secret that so many sound pros have significant hearing deficits. It explains to me why certain recordings have cranked up treble beyond reason. Use your ears! (But protect them for later use!)