Why do you suppose unicorns needed an additional phallus? Wasn't the horse cock enough?

I suppose it is possible the enhancement was invented to boost sales for the flailing wood nymph porn industry.

Or maybe it is just a permanent "fuck you", what with horses lacking proper digits for lewd hand gestures.

I wonder if anyone has written a book on the subject. Surely I can't be the only person curious about this.

Best mythical phallus fit?