ETYMOLOGY
reduplicated derivative of gibber (unintelligible talking, rapid and inarticulate utterance)
EXAMPLE
“…and I wott not what maruelous egges in mooneshine: but a flye for all your flying Speculations, when one good fellow with his oddiestes, or one madd knaue with his awke hibber-gibber, is able to putt downe twentye of your smuggest artificiall men, that simper it so nicely, and coylie in their curious pointes…”
From: Pierces Supererogation
Or A New Prayse of The Old Asse,
Gabriell Harvey, 1593
Lexicophilia 