Butter up

What is Butter up?

Butter up definition and meaning on Dictionary terms:
noun

the fatty portion of milk, separating as a soft whitish or yellowish solid when milk or cream is agitated or churned.
this substance, processed for cooking and table use.
any of various other soft spreads for bread: apple butter; peanut butter.
any of various substances of butterlike consistency, as various metallic chlorides, and certain vegetable oils solid at ordinary temperatures.