act (one's) age

act (one's) age

To behave in accordance with one's expected level of maturity. Really, John, act your age a little. You're like a child sometimes! I'm glad that Sarah is so committed to her studies, but sometimes I wish she would act her age and go out with her friends a bit.
See also: act, age
Farlex Dictionary of Idioms.

Act your age!

Behave more maturely! (A rebuke for someone who is acting childish. Often said to a child who is acting like an even younger child.) Child: Aw, come on! Let me see your book! Mary: Be quiet and act your age. Don't be such a baby!
See also: act
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

act one's age

Behave more maturely. Although the phrase often is used in asking children to act in a more grown-up fashion ( Only babies suck their thumbs; act your age), it also may refer to an adult who is, sometimes deliberately, acting much younger than might be considered appropriate ( Grandpa, it's time you stopped climbing ladders and acted your age).
See also: act, age
The American Heritage® Dictionary of Idioms by Christine Ammer.

act your age

If you tell someone to act their age, you are telling them to behave in a way that is suitable for their age, because they are behaving in a childish way. One patient complained that the nurse had told her: `Act your age and pull yourself together.' Note: This expression is used to express disapproval of someone's behaviour.
See also: act, age
Collins COBUILD Idioms Dictionary, 3rd ed.

act your age

behave in a manner appropriate to your age and not to someone much younger.
See also: act, age
Farlex Partner Idioms Dictionary

ˌact/ˌbe your ˈage

(informal) (often used as a command) stop behaving like a child: You’re behaving like a couple of kids. Act your age!
See also: act, age
Farlex Partner Idioms Dictionary

act your age

Don’t be childish or act foolish. This admonition appears to date from the 1920s. “Be your age” is the caption of a 1925 New Yorker cartoon; “act your age” appears in a 1932 issue of American Speech, a journal that chronicles current usage.
See also: act, age
The Dictionary of Clichés by Christine Ammer
See also:
  • act one's age
  • act your age
  • Act your age!
  • act/be your age
  • courage of one's convictions, have the
  • have the courage of (one's) convictions
  • have the courage of convictions
  • have the courage of your convictions
  • have/lack the courage of your convictions
  • lack the courage of (one's) convictions