What's your favorite proof accessible to a general audience? What math statement with proof do you  find most beautiful and   elegant, where such is  accessible to a general audience, meaning you could state, prove, and explain it to a general audience in roughly $5 \pm\epsilon$  minutes. 
Let's define 'general audience' as approximately  an average adult with education and experience comparable to someone holding a bachelor's degree in any non science major (e.g. history) from an average  North American university.

A proof that needs five seconds rather than five minutes, but I find instructive nonetheless:
Suppose you have a line in $\mathbb{R}^2$ together with two points $A$ and $B$ on the same side of the line. Determine the point where the distance travelled by an object moving from A to B being reflected at the line is minimal.
Too lazy to draw up a diagram. Show people the problem, then reflect one of the points on the line and they will suddenly see...
A great example to show the beauty of mathematics without involving anything abstract or scary numbers. Also a good opportunity to explain some basics.
