Princess Aura: Look! Water is leaking from her eyes.
The Emperor Ming: It’s what they call tears, it’s a sign of their weakness.

— Flash Gordon

I’m of two minds on this one.  There is usually no harm in showing emotion, be it happiness or grief.  But there is a time and place for everything.  If I feel the need to let grief or sadness out, I tend to do it in privacy.  Happiness is something I feel comfortable expressing in public, but I won’t cry in public.  There’s no shame in it when I see others do it.  It’s just something I don’t do myself.