寒い can become 寒くない, which is apparently also an i-adjective. Can it be further conjugated to 寒くなくない?
What about 寒くなくなくない, and so on? Do Japanese speakers regard such expressions as outright ungrammatical or merely silly? (Silly as in, in English, multiple negations like "It's not the case that it's not the case that … it's cold" are silly but not ungrammatical.)
What about verbs? I know the causative-passive 食べさせられる (to be made to eat) is legit, but is there such a thing as, say, potential-causative-passive-potential? In English, "can be made to be able to eat" is perfectly grammatical and can be actually useful, as when discussing an anorexia patient. How would one say it in Japanese?
Is it grammatical to say 食べられさせられられる (食べる -> potential 食べ
るられる -> causative 食べられ るさせる -> passive 食べられさせ るられる -> potential, the final form 食べられさせられ るられる — not sure if I did it right)?
I'm asking this mainly out of theoretical rather than practical interests, but I would also appreciate information about limits of conjugation in ordinary conversation.