We don't have synonyms for chat up yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are chaw up, chats up and chat-up.
(v) :
(transitive, idiomatic) To talk to (someone) in a friendly, open, or casual manner, sometimes also in a charming or affected manner, usually to curry favor, and sometimes flirtatiously with the intention of establishing a romantic or sexual encounter or relationship with that person.
(v) :
(transitive, idiomatic) To talk to (someone) in a friendly, open, or casual manner, sometimes also in a charming or affected manner, usually to curry favor, and sometimes flirtatiously with the intention of establishing a romantic or sexual encounter or relationship with that person.