Just coined it myself.
Creative Lockjaw: A syndrome where an individual has a great idea but can’t quite spit it out.
It happens, most often, when you over-edit yourself. You’ve got that fantastic idea, but you refuse to write it down right away because you want to describe it just so.
Creative lockjaw often leads to idea pfffft syndrome. That’s more serious: You fail to write down or verbalize an idea (because of creative lockjaw). Then you get distracted, or you get fired, or your budget runs out, or your boss decides everything should be purple. And your idea is gone. Pffffft.
I use my trusty Moleskine to fend off creative lockjaw. I will not show anyone the ridiculous scrawls in its many pages. But more often than not, if I say “eh, I’ll write it down later,” I regret it. Same with “I need the idea to take shape first.”
Friends don’t let friends fall victim to this horrible affliction.