butter up

butter up

To be nice to someone, by flattery or other means, before delivering bad news or asking for a favor. I tried to butter up my father by mowing the lawn before I asked to borrow the car. At least butter me up before you ask for money.
See also: butter, up
Farlex Dictionary of Idioms.

butter someone up

 and butter up to someone
to flatter someone; to treat someone especially nicely in hopes of receiving special favors. (See also spread something on thick; soft soap.) A student tried to butter the teacher up. She buttered up the teacher again.
See also: butter, up
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

butter up

Excessively praise or flatter someone, usually to gain a favor. For example, If you butter up Dad, he'll let you borrow the car. This term transfers the oily, unctuous quality of butter to lavish praise. [c. 1700]
See also: butter, up
The American Heritage® Dictionary of Idioms by Christine Ammer.

butter up

v.
To praise or flatter someone in order to make him or her more receptive or willing: My coworker, hoping for a raise, is always buttering up the boss. If we butter up the bartender, maybe he'll buy us a drink.
See also: butter, up
The American Heritage® Dictionary of Phrasal Verbs.
See also:
  • butter up to (one)
  • flattery will get you everywhere/nowhere
  • flattery will get you nowhere
  • get in (someone's) good books
  • curry favor
  • curry favor with
  • curry favor with (one)
  • curry favor, to
  • curry favour
  • nosing