I would get people hurt. Not on purpose, but out of plain stupidity, the results would be disastrous.
I had an experience not too long ago that illustrates this point precisely. We were eating with some missionary friends and some of their local friends, who were unaware of the missionaries' full vocation. I was so nervous about not saying the word, "missionary," that I ended up saying one of the acrostics for a particular meeting where I met these friends. It was certainly not an obvious reference to anything Christian or missions-related, but my friend didn't acknowledge my statement. (It would have required some tricky explanation, had the local friends heard it.) So I said it again. Her face glowed with nervous annoyance, so I decided that the story was worth passing over.
On the way home, I made a preposterous comment about how happy I was that I didn't say the M-word. It wasn't until I was in bed that night that I realized my mistake. Oops! is an understatement. (It should be noted that my friends were nothing but kind. They have a great deal of patience with foolish non-missionaries like myself.)
Thank you, missionaries, for walking the tight rope of guarded vulnerability that bridges the gap between healthy transparency and cautious wisdom. I thank God for the privilege to give to you, pray for you, and love you from my American couch. There's still a large chunk of me that wishes that I could be counted among you, but it is obvious that God knows what He's doing.