Thanks to Happy Days, the pop culture lexicon now contains "Chuck Cunningham Syndrome," which refers to the mysterious and unexplained disappearance of a character from a TV series. After the first season of the sitcom, the eldest son of Howard and Marion Cunningham, and brother to Richie and Joanie, played by both Gavan O'Herlihy and Randolph Roberts, was first sent off to college, before being unacknowledged entirely. In subsequent seasons, the Cunninghams would only refer to their "two kids."
In creator Garry Marshall's autobiography, he writes that whenever anyone asked him about Chuck's disappearance, he would say the character got a 12-year basketball scholarship to the University of Outer Mongolia. Har har. Old people, right?