Is it a poke in the eye with a sharp, or blunt stick?

Is it "better than a poke in the eye with a sharp stick", or "better than a poke in the eye with a blunt stick"?

I suspect that some sort of metaphor testing facility in the Discworld concluded that virtually anything was better than a poke in the eye with a sharp stick, but apart from that I'm not 100% certain.

Side question: is there a term for when a metaphor or cliche gets mutated?

Solution 1:

The Shorter dictionary of catch phrases (Rosalind Fergusson, 1994) has the blunt version.

A dictionary of slang and unconventional English: colloquialisms and catch phrases, fossilised jokes and puns, general nicknames, vulgarisms and such Americanisms as have been naturalised (E. Partridge and P. Beale, 2002) has both:

Solution 2:

The only way I've ever heard the expression is better than a sharp stick in the eye. Mileage will doubtless vary.