Juju is a term used by Humans of West African and French colonial origin to describe a certain type of luck or inspiration, sometimes attributed to qualities of witchcraft.
When Starfleet Ensign Travis Mayweather was assigned to the United Earth starship Yorktown in the 2150s decade, during the Earth-Romulan War, he felt like he was perceived as bad luck, or "bad juju", by the crew of that vessel. He felt that the crews of other Daedalus-class vessels felt the same way, since Mayweather had been the helmsman on duty when the Daedalus-class Discovery had been lost at Berengaria. (ENT - The Romulan War novel: Beneath the Raptor's Wing)
Lieutenant Francis Drake Reed, of colonial islander origin, was fond of using this term in describing activities. He referred to his juju as luck in playing pool in the year 2243, while hustling a group of traders and miscreants on Starbase 2, saying that his opponents would need warp drive-powered pool cues to keep up with his juju. He used the term again when advising George Kirk about the luck that would be required to defeat a group of Romulan birds-of-prey that were facing down the prototype Constitution-class ship they were traveling aboard. (TOS novel: Final Frontier)