A snoot is something you use to constrain the light coming from a flash, you can use it to tight a beam of light, or you can use it to flag light so it will not hit your lens and cause flare.
Scott Campbell came up with this 30 seconds, 2 Dollars snoot that will do just that – snoot your flash. In the process he nuked a catch all sack, but hey! It was worth it. (Kill me if I know how I missed it up till now)