An unusual discovery was made by a Chinese manga fan while reading through old issues of Dragon Ball. In a panel following one with Cell hovering over a village, a resident can be seen with the distinctive straw hat and tank top commonly associated with Monkey D. Luffy of One Piece fame.
At first glance this may seem like a simple homage Dragon Ball author Akira Toriyama made to his heir Eiichiro Oda, creator of One Piece. Especially since both comics are published by the same company, these kind of cameo appearances are not unusual.
Anyway Dragon Ball series was finished in 1995, two years before the first issue of One Piece. Therefore the chances of that straw hat belonging to Luffy are slim to none. Probably it’s just a mere coincidence.