Defined and caused by the actor/director/writer Matthew Gray Gubler. Explained by him in his blog.
What is the gubler-flu you ask?
It's a highly contagious bug running rampant in certain parts of the world.
you will be eager to learn the history of vaudeville,
you will find yourself watching old disney movies,
drinking rootbeer floats,
and carving pumpkins (even though its january),
you may also notice a burning desire to perform magic tricks,
and will most likely grow a thin well manicured mustache (despite your gender).
I have been suffering from Gubler Flu ever since I got hooked on Criminal Minds and Matthew Gray Gubler's Unauthorized Documentary.
Me: Why am I sitting outside carving a pumpkin and drinking rootbeer in January?
Friend: Oh no! Your Gubler Flu is flaring up again!