Eschew Obfuscation
One aspect of Grice's Maxim of Manner is avoiding obscurity. A deliciously ironic 'synonymous' locution of this maxim is to eschew obfuscation, which actually 'shews' in obfuscation as it poses the imperative to eschew it! (Because eschew and obfuscation are both obscure words).
Another such ironic flouting of the maxim of manner is to say, instead of the imperative to 'be brief' to say 'avoid all unnecessary prolixity when possible', which adds up to the same thing but says it in umpteen more syllables. Shakespeare said "brevity is the soul of wit", not "unnecessary prolixity is the essential core of clever repartee".
Thus humor, or at least a certain branch of humor, may consist in purposefully flouting the conventional conversational maxims.
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