A friend of mine has the "Eternal Sunshine of the Spotless Mind" poster on the wall in her apartment. Countless times, she's come in the room, under certain light conditions, seen Jim Carrey's big face making that goofy expression, and screamed and jumped back like someone was in the room with her.
I laugh at this, saying "But you're the one who hung the poster. And you've looked at it a thousand times. You know it's there!"
Sunday during comedy writing class I got a little bored and doodled a little black heart on my right thigh. Three times on my bike on the way home, out of the corner of my eye, I saw the little black thing on my leg, thought it was a bug, and spazzed out trying to smack it off my leg. Three times.