The irreducible complexity (IR) argument was defined by Behe in his book Darwin's Black Box as:
A single system which is composed of several interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning.
IR has become the poster child of the intelligent design movement and played a leading role in the Dover PA trial on whether intelligent design was actual science, which the trial determined it wasn't.
But intelligent design advocates like Behe and the folks at the creationist thinktank the Discovery Institute never seem to stop touting IR as an argument against evolution, despite it having been repeatedly refuted over and over again, most famously by Christian biologist Ken Miller (see here).
So I came up with a term to describe such people who use refuted arguments over and over:
Irreducible Stupidity: Using the same refuted argument again and again and failing to learn from it
It's short and easy to remember. So if you come across a creationist who brandishing IR as a "knock down" argument against evolution, tell them we have numerous examples of biological systems whose parts can be removed that function for other things, including the often cited example of the bacterial flagellum itself. And if necessary, kindly remind them that using the same refuted argument again and again and failing to learn from it is textbook example for irreducible stupidity.