One really interesting thing about being a doctor is that people tend not to tell you the truth so much.
This is apart, of course, from being lied to by patients about things they don't want to talk about, like sex and drugs.
I mean what people tell me about myself. I could have toilet paper stuck to my neck and for most of the day people won't tell me about it. Or I can tell a joke that, in retrospect, is really not funny, and people will laugh.
So I run the risk of making a total ass of myself. I guess this is the historic problem of "telling truth to power": it can get you in trouble, so people tend not to do it.