It'd depend on your definition of meanest. We've had hallucinations and wasps, a murderer and pheromones, network screw ups, random bursts of song, power loss, and more hallucinations. Or so I've heard. I haven't been here for all of it.
So I guess it depends on how much a person values consistent memories, and how well they handle it, knowing it's probably temporary. I'm waiting for the train to fuck with us, have everyone go 'oh, it's temporary' and then have it not be.