(strictly) When in a foreign place, suit behavior or appearance to the local culture. / (loosely, idiomatic) Adapt to the circumstances; follow common custom.

(as imperative) Do not imitate my behavior but obey my instructions.

Alternative form of do as I say and not as I do

(formal) A greeting used upon being introduced to someone. Alternatives are pleased to meet you and nice to meet you. (Sometimes used as a rhetorical question among familiar parties, depending on the region).

(UK, euphemistic) A difficult situation

(idiomatic) To achieve social acceptance or financial success as a result of behaving in a benevolent or charitable manner.

Alternative form of how do you do

If you don't have a lot of money, extend the life of what you have.

plural of how do you do

(idiomatic, colloquial) An intensified version of what? or huh?, expressing surprise or lack of comprehension