in on something

Từ điển tiếng Anh - Cambridge Advanced Learners Dictionary

in on sth idiom
involved with or knowing about a particular activity or plan
• He seems to be in on everything that happens at work.
• She's trying to get in on a research project organised by the university.
Thesaurus⁺: ↑Taking part and getting involved ↑Getting involved for one's own benefit or against others' will
Main entry: in_idiom