Gooey to fit in the nurunuru part. But itches like a hell of just itch if you don't process them right to eat so it fits for punishments and self hatred.
Not just itch. Certain rootcrops are outright poison and can be FATAL on its own. They need to be processed first before they can be edible.
That's the case of cassava here.
That's yamaimo, not cassava. Yamaimo is generally nontoxic even when raw, but they contain tiny, needle-like crystals of sodium oxalate (concentrated near the skin). On contact, the crystals basically inflict multiple tiny puncture 'wounds' on your skin, which itches like hell. This isn't an allergic reaction though, strictly speaking. More like triggering the nerves responsible for sensing pain on a smaller scale (causing itching instead of pain) but over a large area (that's why it itches A LOT).
Yamaimo is generally eaten raw, grated into a gooey paste. Proper preparation of yamaimo (as hinted by Demundo) first involves peeling it thickly (to remove most of the aforementioned oxalate crystals) and then soaking it in diluted vinegar or some other acidic solution to dissolve the remaining oxalates. Now it can be grated and used for food.
(Also, when grated, the starchy, gooey matrix also helps to bind and shield any remaining oxalate crystals, so some people can just get away by wearing gloves and not bothering with the soaking process.)
Of course, some people are also allergic to yamaimo proteins, so they itch even more when handling or eating it (dangerously so, sometimes, depending on severity of the allergic reaction).
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Now, most varieties of cassava are indeed toxic, since they contain glycocyanides, that is, cyanides bound to sugar molecules. The cyanide part gets released under acidic conditions (there's another enzyme(s) involved, but basically the cyanide-sugar bond gets "hydrolysed", similar to how starches get broken down under heat and acidic pH), like in a herbivore/omnivore's stomach. Most bovines are somewhat resistant to glycocyanides though, since they have higher stomach pH (they also have some sort of detox mechanism to remove any released cyanide), but they will still get chronically poisoned if fed on a cassava-rich diet over a long period of time.
Humans, meanwhile, can actually die (from acute poisoning) if they eat the wrong kind of cassava that hasn't been processed properly. For the more poisonous kinds, not even simple cooking or frying can get rid of enough glycocyanide (they actually need to be soaked/boiled/sundried/treated with chemicals before cooking.)
Cassava intended for direct human consumption (as opposed to processing into flour and starches) are of the less toxic varieties ("sweet cassava") though. Simple cooking can render these safe. If you ate steamed/boiled cassava root or fried/dried/baked cassava chips before, that's probably the kind you're eating.
It's sort of like the difference between bitter and sweet almonds, really. Even the toxin involved is nearly the same (basically another kind of glycocyanide.)
Of course, in poorer countries, due to greed or incompetence, the wrong kind of cassava will enter the usual distribution channels sometimes, and you'll see 'food poisoning' and deaths making the news.
(Some of the cases are more likely to be caused by pesticide contamination instead though. People just have a knee-jerk reaction to blame cassava because it's known to be poisonous when prepared incorrectly, especially in the older days when selective breeding hasn't reduced glycocyanide levels for most varieties yet.)
Updated
Eh?Amaaazing!
You can even play Kancolle on an iPhone!!
Because it's HTML5 now.Just how slippery is it!?It's slipping and sliding all over the place, isn't it?
/nururu/ of graphics, smooth; otherwise slippery/slimy/gooey - you can imagine how this would be applied to certain parts of the anatomy.How slippery!?Whaa!?
Did you say slippery!?Mild? Real? Solid? Or maybe WILD!?C'moon!
How slippery?Reaction.About the same as yams, perhaps?This is more the 'gooey' nurunuru