Repeated criticism of this sort is harrassment. Pure and simple.

There is no point in subtlety, cuteness or anything circumspect. Simply stand straight, look him square in the eyes( really at the bridge of his nose, but you probably know that already), and tell him calmly but firmly that you have heard enough, and that he is to stop what he is doing immediately.

Don't argue, don't raise your voice, just lay it on the line, and walk away. And don't ever talk to him again.