know which side bread is buttered onknow which side (your) bread is buttered (on)
to be careful not to upset people who you know can help you.
Ollie won't refuse to come with us. He knows which side his bread is buttered.
know which side (one's) bread is buttered (on)
To know how to best ensure one's success. I know which side my bread is buttered on, so I was very nice to the recruiter and promptly sent her a thank you card after our interview.
know which side one's bread is buttered on
Prov. to be aware of where your money comes from; to be loyal to the person or thing that will benefit you the most. Wife: Please be sure not to upset Grandma. You know we can't do without the money she sends us every month. Husband: Don't worry. I know which side my bread is buttered on.