Here’s an addition to my personal list of villains.
Imagine someone who intentionally leaves their mobile phone on — perhaps even on an extra loud "outdoor mode" and with an particularly obnoxious ringtone — during movies, symphonies, plays, or lectures. While this person isn’t so nasty that they would plan or prompt a call, they enjoy the thrill of knowing, at any moment (but especially during the quiet or emotionally charged parts of the performance), that it could all be ruined. And that it would be their fault. Of course, they would act embarrassed and brush it off as an honest mistake.