Past tense form of 'big' when used as a verb, meaning to have made larger or to have increased in size.
Regular past tense formation from 'big' used as a verb, though this usage is non-standard and rarely used in modern English.
While 'bigged' looks strange to modern ears, it follows the same logic as 'to big up' in slang meaning to praise or make important—language creates new verb forms all the time!
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