think twice about something/about doing something

think twice

To reconsider, be cautious about, or thoroughly contemplate something before committing to it. I'm going to sue them for everything they're worth—maybe then they'll think twice about trying to steal my ideas! Maybe we should think twice about investing so much money in a project we know so little about.
See also: think, twice
Farlex Dictionary of Idioms.

think twice about someone or something

to give careful consideration to someone or something. Ed may be a good choice, but I suggest that you think twice about him. You will want to think twice about it.
See also: think, twice
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

(not) think ˈtwice about something/about doing something

(not) think carefully before deciding to do something; (not) hesitate: You should think twice about employing someone you’ve never met. If they offered me a job abroad, I wouldn’t think twice about taking it!
See also: something, think, twice
Farlex Partner Idioms Dictionary
See also:
  • think twice
  • think twice about
  • think twice, to
  • think upon (someone or something)
  • no stranger to (something)
  • have second thoughts
  • have second thoughts about (someone or something)
  • get second thoughts (about someone or something)
  • chew cud
  • cud