No, I really don't know why this game is called "Redondo." It was called that when it was taught to me, and, dutiful propogator of sociocultural artifacts that I am, I share it with you as such.
Redondo is an art-like game. Art-like in that people draw. But only -like, in that they really don't have to draw anything recognizable. They can scribble and scrawl and doodle, too. In fact, they are encouraged to make drawings that are basically inscrutable, unintelligible, undecipherable, unfathomable; incognizable, inexplicable, incomprehensible, and graphically nonsensical.
Put a stack of paper in the middle of the table, or several stacks, so that everyone has stack-access. Also make sure that each player has equal access to instruments of doodlage: pens, markers, color pencils, crayons. When ready to start, players take a piece of paper and do their doodles. As soon as a doodle is done (becoming a "dondle"?), the doodlist places the paper face down in the middle of the table and says, inscrutably, "Redondo."
As soon as someone says "Redondo," someone else takes the drawing, beholds it in all its incomprehensibility, and waits for the inner meaning to surface. As soon as all is self-evident, she gives the work of doodlage its appropriate caption, appropriately writing the caption in the caption-appropriate area. She then places the titled doodle in a separate pile.
And so it goes, until everyone is tired of making new squiggles, and all the drawings are captioned.
Players then take turns picking from the pile of the titled Redondones, reading the caption while holding the work of silliness for all the beholders to, um, behold, and, with the assurance of a gallery owner and linguistic mastery of an art critic, improvise on the vision, meaning, craft and beauty therein expressed.
And, for some reason, much laughter ensues, and a great time is had by all.
See also: Exquisite Corpse