Grephthosthenes is a well-known (though little respected) figure of mythology to all those who inhabit any of the myriad lands where the shaky, scattered and sometimes downright neurotically inclined Quezlar family can be said to have made their mark. Since X R Quezlar spoke about the famous stein at the opening of the company picnic in -188 EC (one year before his son Rahjoon took over the management of the family's finances) it has been referred to repeatedly in Fefferberry Folklore as well as in the numerous anthologies of fairy tales produced by Archimetres and Troy - owners of The Underfunded Eastside Publishing House for Small and Insignificant Mammals - who thought it was a fairy tail. Although many people question it's actual existence (not to mention it's importance) this author has recently uncovered new evidence that leads to the inevitable conclusion that the clinically insane might be "onto something" (as opposed to "on something" which is a well-known and un-repudiated).
In -185 EC, a little-known archeologist (i.e. grave robber) called Maxilla von Sims found several articles at one of her smaller digs (i.e. a cheap job that really should have been done by somebody else). One of the items happenewd to be a hat which although disintegrated to a point where it was almost unrecognizable as such still had the remnants of an off-green feather stuck in a narrow yellowish band along which the words "Ey wer kilt bi Grefosth" were written in a crude handwriting. This author made contact with Rubella von Sims (the only descendant of Maxilla who actually stuck around long enough to be registered as a local citizen) and recovered some scraps of the hat. Upon greater study it is possible to assert (though not confirm) that the handwriting is in fact not that of a giant. It is believed that the inscription was made by one of the giant's prisoners in an attempt to market the huge individual's unique talent: bopping somebody over the head so hard they never get up.
Indeed, it would seem that the writer was trying to write "I was killed by Grephthosthenes" and ran out of space, time, or both before the work could be completed. In and of itself then, the hat lends only a small amount of credence to old X R's rantings.