Why Do Cubs Fans Throw Visiting Teams' Home Run Balls Back On the Field?

They never show it on TV because it encourages bad behavior; behavior that gets you kicked out of other baseball stadiums...
...But when a visiting team hits a home run at Wrigley Field, which they oftentimes do, it considered poor etiquette to keep the ball. The more refined way of handling the situation is to throw the ball back on the field as people are chanting "Throw it back! Throw it back!"
Shrog and Bob were at the Cubs vs. Rockies game in September 2023 and witnessed two home runs from the visiting teams. Shrog learns a valuable lesson on the origin of this tradition and how to catch a ball in the bleachers.