Lady Mannheim's Finishing School for the Second-Sighted

It was neither Friday nor Saturday, nor June or July, but some time in-between, that Mr. and Mrs. Null of Groper's Gully welcomed the arrival of their triplets, three healthy girls whom they named Severance, Catafalque and Woe.

On that very non-day, a half-unicorn came to town, burning for revenge.

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According to the Urban Dictionary, half-unicorns come in several flavors:

• Manacorns (manatee + unicorn), 
• Unicats (self-explanatory), 
• Dolphicorns (ditto), 
• Liocorns (huh), 
• Dragicorn (not a unicorn in drag, but dragon + unicorn), 
• Humicorn (human + unicorn, the kind I had in mind for this prompt)

Not that this poses a significant threat to the continuance of our species. Now, why don't we look in on Mickey Mouse's haunted house adventure from way, way back (1929).