I chose It's a Wonderful Life.
My fav scene in the bridge toll booth. J Clarence (the angel) jumps in the river and Mr. Baily jumps in to save him. They sit in the toll booth hanging their wet clothes to dry. The toll booth guy is sitting there listening and minding his own business. He is about to spit his tobacco, when Clarence makes a "wild" claim about being an angel. The toll booth guy stops dead cold and stares at Clarence. His expression is fabulous.