when the junkie sitting beside you on the bus starts talking to himself
one of my most terrifying experiences was when I was on the bus coming home from the dentist and the only seat free was next to this junkie guy. I sit down and I notice he has a unlit spliff in his hand and soon enough he starts talking, not muttering, but proper loud talking, borderline shouting about God and religion and so on. This goes on for ten minutes or so, before it's his stop.
He stops being crazy, turns to me and politely asks for me to make space for him to get up and leave.