A big part of the social interaction among physicists is how you are perceived. And sometimes such perception can be very important, such as whether or not you get invited to a conference, to what extent people seek you out for collaborations, etc. Don't get me wrong, much of those depend almost entirely on politics and power, but not all.
Maybe lots of young physicists know this, but there must be some out there like me who have to get whacked in the face with this kind of stuff. In high school, people thought I was smart. Not because I answered all the teacher's questions or tried to show how smart I was. In fact it was the opposite. The less I interacted, the smarter they thought I was. It was the not-so-bright people who were always
trying to show how smart they were.
But in physics, it seems the presumption is that one is dumb...well not dumb, but not so bright. So those who jump up at conferences, and ask probing questions, they get the respect. Those who gush over the latest physical results, especially those slightly out of one's field, they get respect. This may sound obvious, but what confounds me is that even these same people who say things incorrectly do not seem to get penalized for the mistakes! And even when they expound about stuff that surely everyone in the conversation already knows, they get respect. That makes no sense to me.
I avoid making mistakes. I don't try to act like the smartest one in the room. I want my performance (i.e. papers) to speak for themselves.
Anyway, so my advice to the youngins for whom the above is not obvious is to practice this early. Learn to speak like a physicist. Always have questions ready and don't be paranoid that they're obvious. Practice talking about all sorts of physics as if you're an authority. It probably helps to try it the first time on inconsequential people.
Hope I don't sound too cynical.