The sound an owl makes; or something that is very funny or entertaining.
From Old English 'hoot,' which is imitative—the word imitates the actual sound. It has Germanic roots related to 'hüten' (to watch or guard), as owls were associated with watching.
Owls' hoots are so distinctive that ancient Romans believed owls could predict death by their calls—so when something became 'a real hoot' (hilarious), people were probably joking about being scared by the sound!
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