Is it bad to lie about your age?

I'm 31, but I always shave off 5 years of my age when they ask me about it. I can get away with it because I look some years younger than I actually am, and most people assume I am 25 when I respond "How old do you think I am?".

Unless I have to show my ID Card where my actual date of birth is mentioned, and it feels very awkward when I have to.

Is it bad to lie about your age?
Post Opinion