ETYMOLOGY
from pig + whisper
EXAMPLE (for n. 1.)
“… Frank.
Yes, sir; there are tailors, shoemakers, milliners, perfumers, dancing-masters, music masters and boxing masters.
Tickle.
I’ll be with them in a pig’s whisper.
Frank.
Pig’s whisper! what a fellow for a gentleman’s tutor! O! he’s a shocking dog!…”
From: Tony Lumpkin in town: A Farce
By John O’Keeffe, 1780
Lexicophilia 