Past tense: acted in a silly or foolish manner, or played the fool.
From Middle English 'daffe' (to be foolish), possibly related to Old Norse or Germanic roots meaning 'foolish'; 'daffed' is the regularized past tense.
The word 'daff' is mostly British dialect now, but 'daft' (foolish) is still super common—showing how sometimes we keep the adjective but lose the verb form!
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