Logically?

Jar Jar Binks is arguably the most idiotic, useless character ever introduced in a Star Wars movie/book/comic book/TV spinoff series. Thusly, he has also been the reason for the creation of hate sites such as [URL removed by moderator] (caution: this site is miiiiighty...frank...in expressing its hatred for our resident Gungan), and upon these pages are lists upon lists stating reasons (and methods) for Jar Jar's timely death. But in spite of all those lists, there is one main, logical reason why Jar Jar should have died in the movie.

Jar Jar Should Have Died On Tattooine.

We can safely assume that Jar Jar, as a Gungan, was spawned on Naboo. Naboo, as depicted in Episode I, is a lush, green planet with lots and lots of water (H20). We can also safely assume that he is also an amphibian of some sort, albeit an incredibly irritating amphibian, but an amphibian none the less. The definition of an amphibian, according to Dictionary.com is:

am·phib·i·an n.

1. A cold-blooded, smooth-skinned vertebrate of the class Amphibia, such as a frog or salamander, that characteristically hatches as an aquatic larva with gills. The larva then transforms into an adult having air-breathing lungs.
2. An animal capable of living both on land and in water.

Obviously, Jar Jar is a Gungan. The Gungan city is underwater (see: Episode I, scene where Obi-Wan crash-lands on Naboo after escaping the Trade Federation station), yet Gungans can also survive on land (see: Episode I, the big honkin' battle on Naboo at the end of the movie). According to the second definition of amphibian, that makes them amphibian. Therefore, Jar Jar is an amphibian. *Author realizes how patronizing that last paragraph was, but leaves it in because it's an important point*

It is common knowledge that most amphibians need to stay fairly moist which requires water, with a few exceptions. Toads have dry pebbly skin that allows them to stay out of water for quite a long while, and there are several other kinds of amphibians/fish that can stay alive during droughts by sealing themselves up in coccoons made out of mucus. However, Jar Jar is not a toad, rather, he is a large, ducklike amphibian creature with a Jamaican accent who doesn't seem to have much in the way of mucus (stupidity, on the other hand...). In that case, he probably needs a lot of water to keep him out of the category of Dead. No problem. Naboo seems to be pracically oozing the wet stuff. But enter Obi-Wan and Qui-Gon, who manage to drag Jar Jar to Tattooine, which, judging by the landscape which consists mainly of sand, sand, sand, Hutts, dewbacks, banthas, womp rats, Sand People, and yet more sand, seems to be slightly lacking in the H₂0 department. Tattooine also has two suns that rise and set at virtually the same time (see: Episode IV, the scene where Luke is looking for Threepio), which would make it even hotter and drier.

We can now safely assume that Tattooine is a hot, arid planet, which is definitely not beneficial to staying moist. Therefore Jar Jar should have dropped dead of dehydration within the first hour of landing on Tattooine, instead of staying irritatingly alive and well until the end of the movie.

One Last Reason For Jar Jar's Death

Jar Jar got his tongue stuck in the energy-bar thing that keeps the pods together on the pod racer. Now, the energy coursing between the pods is probably related in some way or another to electricity, and there would have been a lot of it in order to keep objects as large as the pods together through the race. As we know, a lot of electricity, or energy of any kind, is usually enough to kill a normal human being (see: The Green Mile, miscellanious electrocution scenes). Jar Jar seems to be vaguely humanoid or at least roughly the same size/shape as a humanoid, therefore, if he didn't drop dead of dehydration (which he obviously didn't), he should have died when he got his tongue caught in the current.