If you want people to sign up for your class, don't call it Bayes Theorem, or anything equally boring (not many people can even pronounce "representativeness heuristic" on the first try).

Maybe something along the lines of "One fraction to rule them all" or "When a 99% positive test is only accurate 1% of the time" or something similarly catchy.

I think 'Bayes' Theorem' (but perhaps not Bayes's Theorem) is catchier than the latter two suggestions. Also clearer.