“Butter someone up” means to flatter or praise someone excessively, often to gain favor or influence their actions. It’s an informal idiom suggesting insincere flattery for personal gain. 

For example:

He tried to butter up his boss in hopes of getting an extra day off.

Stop trying to butter me up! I know you want something. 

The magazine tried to get her to write an article by buttering her up.

She was always buttering up her professor before asking for an extension on her essay.

He knew she was looking for her next role, and he wanted her in his movie, so he was ready to butter her up.

The bank has to butter up investors because it is in a fiercely competitive market.

Tradução:

“Butter someone up” significa bajular, adular ou fazer gentilezas a alguém para conseguir algo em troca. Em outras palavras, é quando alguém tenta conquistar a boa vontade de outra pessoa, geralmente através de elogios exagerados ou favores, com a intenção de obter um benefício próprio.