Conspicuous Consumption - as it was done in 1903.
In order to celebrate the completion of his $200,000 stable, C.K.G. Billings held a "horseback dinner" on March 28, 1903 for 33 of his pals from the Equestrian club. It took 24 workers three days to convert the second-floor banquet hall at Sherry's restaurant in New York into a faux rural barnyard and stable.
The guests ate while seated on their horses. The various courses were served on a table attached to the saddle. There was an individual waiter for each rider, and a groom stood at each horse's head to keep it calm and prevent a sudden start from spilling the food. More details from the NY Post-Dispatch
(Mar 29, 1903) :
Each horses was equipped with a white, quilted satin saddle and bridle, martingale and shoulder-hangings in gold and white. Each guest was designated to his place by his name lettered in gold on the cantle of a saddle.
In the center of the horseshoe formed by the animals was a mound of green, surmounted by a mass of flowers. The grassy sides sloped off into a lawn, which spread to the horse's fore feet.
Beside each horse was a satin upholstered mounting box, from which the diner in the saddle was served. A board fastened athwart the pommel of the saddle served as a table, and that the steed might not curvette or prance or shy, and so spill gravy or salad, a liveried groom stood at each horse's head...
The equestrian guests entered fully into the spirit of the affair and soon the first banquet in the saddle was in full swing. And while the guests ate, so did the horses. While the courses were being served from the mounting blocks to dishes which were secured in holders on the saddle tables the horses munched oats from individual silk-covered mangers.
Twelve courses were served, then the tables were removed from the pommels and the guests lounged over their cigars in the padded saddles. Speeches followed, mostly laudatory of Mr. Billings.
It cost Billings around $1.3 million (in modern money) to host the event.
The Town Talk - Mar 27, 1903
Reference: Museum of the City of New York