Yaga yaga

Having just heard it on the radio this morning, I now have "OK Fred, now you're a yaga yaga" (Errol Dunkley) on the brain. But what on earth is a yaga yaga? Google is most uninformative.
  • Current Mood: curious curious
  • Current Music: "OK Fred, now you're a yaga yaga" in my head
I always heard it as 'yukka yukka'. Not that that makes it any clearer. And now I have it as an earworm too. :-)
I actually heard it as "yugga yugga" but Google assures me it is "yaga yaga". Sadly, though, Google is silent on the issue of what "yaga yaga" might mean.
It seems there's an album of that name, but other than that I'm no more informed than you.