Dooking is that wonderful chittering sound ferrets make when they're
excited or agitated, like when they're doing a weasel war dance or chasing
and chewing on each other.  Some ferrets are more likely to dook than
others; by nature they're usually silent and they generally have to get
pretty riled up to start dooking.
 
In the past, I've described it as, "Er er er er er!"  Others have described
it as, "Dook, dook, dook, dook, dook!"  And there have probably been other
renditions.  Once you hear it, you'll know it.
[Posted in FML issue 3652]