"Dragon Ball AF (ドラゴンボールAF, Doragon Bōru AF) was the subject of an "April Fool's" joke in 1997 (following the end of Dragon Ball GT, the third and last series), which concerned a fourth anime installment of the Dragon Ball series. It has since gained popularity, been the basis for various fictional works by fans, and has even resulted in a dōjinshi series produced by Toyble." Taken from te Dragon Ball Wiki