Maybe Okrand want to prank us by not telling the noun {chem}?
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The difference between chem (prank) and *toj (deceive, trick) can be seen from the original request. (qep'a' 2020 Q&A)
Although not said explicitely, it seems like chem is related to pranking for fun or joking while toj includes intentional deception connected with aggression, but not only.