According to Wikipedia and various other sources,
"Anatidaephobia" is an irrational fear that a duck is watching
you.
It is not a real phobia. It comes from Gary Larson's The Far
Side.
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Anatidaephobia: The fear that somewhere, somehow, a duck is watching you. This answer was found in The Farside Gallery 4, by Gary Larson, page 61, lower right.
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I'm experiencing it right now, so that makes... one.
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The fear of someone watching you is called Anatidaephobia.