"He's everywhere you wanna be!" - Troy McClure speaking of Jub Jub, "A Fish Called Selma"

It was in the episode "Selma's Choice" of The Simpsons that Selma Bouvier inherited her late aunt Gladys's beloved iguana, Jub Jub. He isn't mentioned very often and he's seen even less, appearing only in his debut episode, then in "Duffless" (where he fears the sight of Selma holding a Tupperware bowl over her head), and later in "A Fish Called Selma" in which Selma married actor Troy McClure and moved to his neo-futuristic seaquarium home. Years later he cameoed in "Goo Goo Gai Pan" when Selma feared he would eat her body after she was dead (he does nibble on a toe). His hobbies include eating microwaved bugs, sitting on big hot flat rocks, and listening to Selma sing. Selma sees him as a substitute for caring for a baby, treating him as her own little child and thus satisfying her maternal instincts.

Of all the names one might consider for an iguana, why "Jub Jub"? During the fourth season of the series writer/producer Conan O'Brien (later of late night talk show fame) was sitting around with the other writers and trying to come up with an appropriate iguana moniker. Eventually, in a momentary pause in brainstorming, O'Brien blurted out the nonsense word "jubjub" to fill the silence, and the other writers decided that Jub Jub was a suitable name as by this time they just wanted to name the reptile and move on to something else.

Despite his limited screen time, there is actually a licensed Jub Jub action figure. He comes packaged with the Selma figurine as an accessory.

DejaMorgana says "It's not "just" a nonsense word. It's from Through the Looking Glass. In the poem "Jabberwocky", Alice reads the line "Beware the Jubjub Bird, and shun the frumious bandersnatch."


References:
The Simpsons Season Four DVD
http://www.snpp.com
http://www.simpsonscollectors.com/wospdb/figure.asp?fig=F0086&env=E0001