The title is a play on "the gay nineties," the decade in which this short is set.
Plot[]
A colony of ants surreptitiously invade a young couple's park picnic in the 1890s and contrive to steal their food. The gags include a scene in which the ants, frustrated three times in their efforts to make off with a sandwich, spread mustard on the back of the girlfriend's hand and trick the boyfriend into biting it, and one in which a female ant sings an overly melodramatic song ("Time Waits for No One") which gets the other ants to run for cover.