I can read from my screen (documents, manuals, news, blogs) without fidgeting causing a few buzzes throughout the day. To avoid being cast into darkness, I'll non-chalantly wave my hand and occasionally throw in a friendly "Hi"; as if trying to snap a person out of daydreaming.
And as luck would have it, because my office door is open, someone would be sauntering by right in front of the doorway when I'm talking to the light switch. Inevitably, they'd hear something, turn in my direction, see me waving, assume I was talking to them, and wave hesitantly with the reply, "Oh... Hi." Now everyone probably thinks I'm the nicest temp around the office.
Two even came in to start a dialogue. Stupid light switch.