You should lie when there is outsider involved and you are at risk in revealing your Zevist identity, or speaking truth where is not a place for it to do and with wrong people where there is a danger of getting killed or whatever, you have to be experienced with life, and not reveal to someone who are not deserving, if any outsider at all, instead say something superficial, without getting too much attention, or if it is a jew, sure better lie for your own sake if you are not experienced yet how to speak with finding your way in silence. Silence is Golden.