Nobody Here but us Chickens?

What does the phrase nobody here but us chickens refer to?
I've always wondered if it was some inside joke between admins or something.

forum #25169

i cant believe i forgot i asked that... wow... well nevermind my senility. My early onset senelity has been... ugh... what was i talking about again?

I've a feeling I first came across the phrase watching Scooby Doo.

flamingmo! said:
What does the phrase nobody here but us chickens refer to?
I've always wondered if it was some inside joke between admins or something.

hmm... I never questioned the order of which the natural balance of the universe follows... if it weren't chickens... it would have been frogs. n.n