1 Spanners: *crunch*crunch*
1 Iki Piki: What are you eating?
2 Spanners: Cockroaches. I like the chitin. What do you eat?
3 Iki Piki: Chopped worm sandwiches.
3 Spanners: EWWWW!!!
4 Spanners: How can you eat dead food?! That's disgusting!

I made an alternative version of this strip:

It took some experimenting to get a photo that clearly looked like I was trying not to throw up, and I don't really think I nailed it. Also, the text doesn't flow as well in this version. I think the pause enforced by the new panel between Spanners saying "EWWW!!!" and the punchline makes the gag funnier, and the panel with me in it is basically superfluous.

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2011-12-02 Rerun commentary: Chitin is an organic polymer produced by a wide range of invertebrate animals for use in hard structural body parts such as the exoskeletons of insects, crustaceans, and other arthropods, as well as the beaks of squid and octopuses. It's made of chains of molecules similar to glucose. Functionally, chitin serves a similar purpose to keratin, which is a similar horny substance made or proteins and used by vertebrates for moderately hard body parts, such as: mammal nails, claws, horns and hair; feathers and beaks of birds; and shells and scales of reptiles.

You might think that eating chitin is pretty yucky, the most obvious sources of it being arthropod exoskeletons. But there's another class of living thing that uses chitin: fungi. Fungi use chitin in their cell walls to give them structural rigidity. Every time you eat a mushroom, you're chewing on chitin.

Chitin, incidentally, was first unravelled chemically by Albert Hofmann, as his Ph.D. project. Hofmann is more famous as the man who gave the world the psychedelic drugs LSD and psilocybin. Both of which can be extracted from... fungi. The guy sure had a thing for mushrooms.