Specialized weapon wielded by Princess, a member of G-Force, in Battle of the Planets. The cord of the yo-yo was as long as was artistically necessary; the yo-yo would detonate as soon as she triggered a charge along the cord.
The explosions were as impressive as 1970s-era anime explosions could get, but the bad guys (agents of the planet Spectra) never got killed. (Presumably the agents went on to extremely successful careers never getting killed on the G.I. Joe show.)
In the original anime show that BotP was based on, Gatchaman, "never getting killed" was rarely an issue when dealing with this yo-yo of death. American film editors saved many animated lives in the production of Battle of the Planets.