Defending Kimura from the Guard?

One of the great things about watching the fifth season of The Ultimate Fighter was listening to B.J. Penn coach from behind the cage. I can't think of a more awful jiu jitsu hell than having to compete against a guy B.J. was coaching (assuming the guy is actually taking B.J.'s advice which, as we saw, was not always the case ...)

I thought I picked up a defense to the kimura from the guard. B.J. was coaching Maynard, who was fighting Nate Diaz (Nick's little brother). Diaz had Maynard in guard, and was attacking with a kimura.

B.J. kept yelling: "try to push your head between your shoulder and his shoulder! Move your head to the middle!"
I'm not sure exactly what B.J. meant. So this little bit of jiu jitsu soltaire should help me ponder the problem for awhile.