"Mumbo jumbo" (sometimes with a hyphen between the words) is a phrase of uncertain origin; the best guess is that it comes from the Mandingo languages of Africa. Webster's Unabridged Dictionary says "Perhaps from the native name of an African god. Among the Mandingos of the western Sudan, a bugbear by means of which the women are terrified and disciplined by societies of the men, one of whom assumes a masquerade for the purpose; hence, loosely, any Negro idol, fetish, or bugaboo." (The Encyclopedia of Word and Phrase Origins says the god's name was actually "Mama Dyanbo" and The Morris Dictionary of Word and Phrase Origins renders the original as "ma-ma-gyo-mbo.")
This usage goes as far back in English as 1738 ("At Night, I was visited by a Mumbo Jumbo, an Idol, which is among the Mundingoes a kind of cunning Mystery." Travels in Africa by F. Moore) but more recent explorers and anthropologists don't seem to have found any African god or being with a a name along these lines. Nonetheless, English speakers continued using the name; it made it into Vachel Lindsay's poem "The Congo" in the 1917 anthology The New Poetry, which contains repeated references to "Mumbo-Jumbo, God of the Congo ... Mumbo-Jumbo will hoo-doo you."
From this idea of a person dressed up as a god to deceive viewers, the phrase gained the additional meanings in English of
"Mumbo Jumbo" has become a popular proper name. It is the name of:
- An online anagram game by Amherst Lodge
- A different online game on Tams11.com in the goal is to make the largest word possible using connecting letters on the board
- A computer game company (started by former employees of Ritual Entertainment)
- A novel by Ishmael Reed
- An English toy store
- A 2000 English fantasy movie, The Mumbo Jumbo (in which Mumbo Jumbo is the name of "a mythological Sprite from the sixth century")
- a store in Coral Bay, Virgin Islands
- a single by someone called Marina on MRK Records
- A Canadian band (Well, their full name is the Mumbo Jumbo Voodoo Combo)
- As just "Mumbo Jumbo," a side project of two DJs, "Mitch Davies a.k.a Dj Kuma, actually working for Transient records and well known for funky well mixed sets, and Bilbo Bagginz a.k.a Cosmosis, one of the pioneers of Psychedelic trance music," according to Turbo Trance Records, which released their album Speaking in Tongues. Thanks to Myrkabah for pointing me to this info and telling me that they're "probably most famous for their track "Weird, Sick, Twisted", which has samples of Homer Simpson."