in yout definition the uncooles person would be someone, who desperately tries to appear cool and fails at it, thus the person who doesn't care about coolness won' be the uncoolest.
theory:
there are at least two types of people rendered cool. the first one is cool by nature, such person ist even cool when looking rediculous, the other type only appears cool, as soon as such a person stops trying to appear cool he or she starts to appear rediculous. the natural coolnes is proportional to confindence, the artificial coolness is much more complicated.