noun, noun or participle which takes 'suru'
beating someone up thoroughly; hitting endlessly
Colloquial and vivid; implies a relentless, comprehensive beating, often in a gang or bullying context. The タコ (octopus) element adds a rough, slangy feel.
不良グループにタコ殴りにされた。
I was beaten up thoroughly by a gang of delinquents.
あいつをタコ殴りに
I want to beat that guy to a pulp.