Butter you up

Generated image of a salesman buttering up a customer
To butter someone up means to give someone a lot of compliments or kind words so they will be flattered and agree to something you want. The person may be trying to persuade or influence you by being extra friendly.

The phrase comes from an old custom in parts of India where people offered balls of butter to statues of gods as a way to ask for help or favor. Over time, the idea became a way of describing flattery used to get something.

He kept telling his boss how brilliant her ideas were, clearly trying to butter her up before asking for a raise.