face itch
An annoying itch that appears on one's face when their hands are engaged in an important activity (primarily video games) and cannot be used to alleviate the itch without negative side affects. The face itch only appears at these inopportune moments and would not otherwise appear when the itch could be easily scratched.
Johnny got a face itch just as he was about to own his friend at madden. He took his hands off the controller to scratch his face and messed up the play; Johnny lost. Stupid face itch.