Most of you will have read, or maybe even used, Debian GNU/kFreeBSD, which is an operating system consisting of FreeBSD kernel with a GNU userland, but there’s also Gentoo FreeBSD.
So what is Gentoo FreeBSD? According to the Gentoo FreeBSD project page, Gentoo/FreeBSD (or Gentoo/FBSD, or G/FBSD) is an effort to create a complete FreeBSD-based Gentoo system, sharing the complete administration facilities of Gentoo with the reliability of the FreeBSD kernel and userland. An experimental, yet incomplete release have been done, and it’s possible to install Gentoo/FreeBSD following the install guide.
I don’t think I’ve referred to Gentoo FreeBSD before.