Most cheeky; having the highest degree of playful boldness, disrespect, or impudence.
From 'cheeky' + '-est' superlative suffix. The superlative indicates the maximum degree of the quality described by the adjective.
British speakers use 'cheeky' so much that 'cheekiest' feels totally natural there, but if you say it in American English, people might be confused—it shows how the same words can have completely different cultural frequencies!
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