We don't have synonyms for chum up yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are chums up and crum up.
(v) :
(idiomatic, informal) To be friendly toward (with or to) someone, especially in an ingratiating way; to form a friendship (with).
(v) :
(obsolete, UK, prison slang, transitive) To initiate (a new prisoner) through a ritual involving beating him with sticks and swords, accompanied by music, to extort money from him.
(v) :
(idiomatic, informal) To be friendly toward (with or to) someone, especially in an ingratiating way; to form a friendship (with).
(v) :
(obsolete, UK, prison slang, transitive) To initiate (a new prisoner) through a ritual involving beating him with sticks and swords, accompanied by music, to extort money from him.