chum up with
chum up with (one)
To be friendly with someone Why is Patrick chumming up with me all of a sudden? He's usually so distant.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
chum up with someone
to become friendly with someone. He seems to have chummed up with Fred. Juan quickly chummed up with all the guys in his class.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.