E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A piece of fun, a practical joke. The Scotch say of a man who indulges in intoxication, He goes the rig. The same word is applied in Scotland to a certain portion or division of a field. A wanton used to be called a rig. (French, se rigoler, to make merry.)
He little thought when he set out
Of running such a rig.
Cowper: John Gilpin.
Rig. To dress; whence rigged out, to rig oneself, to rig a ship, well-rigged, etc. (Anglo-Saxon, wrigan, to dress; hrgl, a garment.)
Jack was rigged out in his gold and silver lace, with a feather in his cap.LEstrange.