The area that is known by most unknowledgeable humans as the "Knee". That modern (but incorrect) definition of the crunklespot is, in actual fact, what an idiotic human back in the Ice-Age called his crunklespot. But now you know! your "knee" isn't your "knee" any more! 'Tis your Crunklespot!
The cave man pointed to his Crunklespot and said "Hee Hee OOGA BOOGA SHASTO KNEE!" and the name stuck for ever.