Sentence:  Of course there are some kids who <WSD>get stuck into</WSD> him, and sometimes that′ll make him curl up like a poked snail. But they don't do that very much anymore, because most of the other kids <WSD>get stuck into</WSD> "them" when that happens. 
Meaning of the word marked with <WSD> tags:  To criticise someone; tell off; to get angry at; to attack.