I caught the first few minutes of Saturday Night Live the other night, which was hosted by Topher Grace (it was a repeat from sometime in January). During his opening monologue, Topher took mock questions from the audience, and someone asked him something I’ve actually been wanting to know, namely: what’s up with Topher? (It’s pronounced, as you might imagine, [ˈthoʊfɚ].) Topher then explains that, like Chris, it’s short for Christopher.
Well, it’s not really like Chris — regular hypochoristic (nickname) formation in English usually involves copying a stressed syllable plus some amount of following material; thus, Elizabeth can beget Liz or Beth because both of these syllables are stressed; Zabeth would be strange, as is Topher. Clearly (to me, at least), it’s just based on the spelling: what you get when you chop Chris off of Christopher is topher; capitalize it and you’ve got Topher.
Then, of course, there’s the issue of how to pronounce this. Clearly, you can’t pronounce it like the topher of Christopher, because that would give you something more like [təˈfɚ], with final stress and (consequently) no aspiration on the initial [t]. So you just reimpose English stress on the result of this odd formation, and you get [ˈthoʊfɚ].
The person who asked the question (and recall, these were mock questions; the “audience members” were really members of the cast) then said something like: “Oh, so I suppose I can name my son Matthew and then call him Thew.” But Thew was pronounced [ˈθuː], not (as I would have expected) [ˈθjuː]. So what’s up with that?