behave oneself

English edit

behave oneself (third-person singular simple present behaves oneself, present participle behaving oneself, simple past and past participle behaved oneself)

To act in a polite or proper way.
His mother threatened to spank him if he didn't behave himself.
- 1912, Stratemeyer Syndicate, chapter 1, in Baseball Joe on the School Nine:
  "That's what happened to me the last time you fired a high snowball. Peaches. That's why I didn't want you to try another while I'm around. You wait until I'm off the campus if you've got to indulge in high jinks. Come on now, fellows, since Peaches has promised to behave himself, let the merry dance go on. Have you tried a shot, Joe? Or you, Sister," and Teeter looked at the newcomers.

to act in a polite or proper way — see behave