Tu quoque

Tu quoque is basically a fancy way of saying, "No, you shut up!"

A latin phrase meaning "Thou, also", this argument asserts or implies that a certain position is false or should be disregarded because its proponent fails to act consistently in accordance with that position. It is an attempt to show that a criticism applies equally to the person making it, and, as such, can be considered an ad hominem argument, since it focuses on the opposite party itself, rather than their position.

Examples of this kind of argument can be seem in the "Atheism is based on faith" and "Atheism is a religion" apologist attacks on atheism.