It’s the name that history attaches to Measure for Measure, as originally performed. And it plainly evokes images of someone shaking someone else’s beard — a sign of disrespect used by Shakespeare himself in both Hamlet and King Lear — as far as I know, nobody has seriously wondered why that name might have appeared beside Measure for Measure in the Stationer’s Register. It’s normally simply listed as one of many misspellings of the name that appeared during Shakepeare’s lifetime.
In fact, the most serious treatment that the meaning of “Shaxberd” has received is an article from 1916 suggesting (facetiously of course) that Shakespeare was, in fact, a barber.
Since this site is about meanings of Shakespeare that seem pretty obvious but have not (yet) been accepted, Shaxberd seems like good name for the site.