The story
From a well-known rule in improv acting, wherein improvised lines must (figuratively) be answered with yes and... in order to continue the scene.
Etymology from Wiktionary, CC BY-SA 4.0.
yes and
Today it means: To go along with what is offered, especially in a performative context, and to accept and expand upon it; to go with the flow; to take it in stride. Full definition →