MCH - pretty obvious. My real world initials.
I signed up as a FReeper back in '98 without spending much time lurking or otherwise paying attention to user names. By the time I realized the value of a clever and memorable handle, I'd already registered and it was too late to do anything about it.
I have already told the few that asked, but my nick comes from my music. I had just been required to produce a sound like the song of the humpback whale on my electric bass, in concert, and that same night registered on FR. I was still thinking 'whale' at the time but didn't want to be known as HumpbackWhale and wanted something related however distantly to political conservatism, ergo, RightWhale.