ETYMOLOGY
of unknown origin;
possibly a variant or alteration of shanny-brained;
from shanny (bashful, shy) + brained
EXAMPLE
“… But while I take this shay-brain’d course,
And like a fool run to and fro,
Master, perhaps, may sell the horse!
Therefore this instant home I’ll go. …”
From: Wild Flowers; or, Pastoral and Local Poetry
By Robert Bloomfield, 1806
Lexicophilia 