Sometimes the urge or need to say ‘I don’t know’ is taken away by the fear of admitting you don’t know.
Sometimes it’s admitting to your kids you don’t know why the sky is blue or admitting you don’t know how the interest rate change will affect their savings account or their pocket money.
Sometimes it’s admitting to your colleagues, either those more senior or junior to you, that you don’t know the latest changes in a project deadline, the latest version of the strategy document (or even where it’s filed), etc.
If you don’t know something, my experience shows you will always be caught out eventually if you bluff your way through it. Please just own up to it and admit you don’t have the latest forecast, project timeline, update, communication, strategy, etc.