Actually it isn't legally or humanly wrong to show your real emotions in public. But it's just the way our society works. Think about it, if you showed your real emotions at work, and still managed to complete your job, people would still term you as 'un-professional', because they think that that sort of behaviour would disrupt everyone else's performance (which is probably true). You see, human beings are taught to handle personal matters discretely, and if you suddenly expressed your strong emotions to a person you'd probably throw him/her offguard. And of course the real key to having successful friendships and acquaintances with people is that you can control your emotions around them. You may feel angry, but you don't directly hit out at them, right? But if you're overjoyed, well then, I guess there isn't any harm in expressing yourself. \nRemember, it isn't wrong to show your emotions (and it's good to learn to control them), it's just that people are not used to it.