Yes, it may sound like a paradox. But no matter how much self-contradictory it may appear, this is a concrete fact. Too much sobriety can sometimes get counter-productive, thereby resulting in misbehaviour.
Actually when you are too much sober, you get extremely conscious about each and every word that you speak, and also about each and every movement and action (like walking, sitting, etc.) that you come up with. You start maintaining a strict control on your words and also gestures and body expressions while interacting with somebody. This makes you sound very cold and indifferent to the other person, thus making you look somewhat proud.
The “sobriety maniacs” must remember that being reserved and soft-spoken does not mean being rudely cold to other people. You certainly have the right to talk less, but that does not mean that you will not talk at all. Please talk to people (OK, talk less if you wish), interact with them, and exchange a little pleasantries. Otherwise you will prove yourself to be impolite.
In a nutshell, if you are too sober in your demeanour, then in a bid to prove yourself sober you are actually proving yourself to be unsocial and uncultured. And that is certainly one of the greatest ironies of your life.