Quoted from http://rcmsgifted.blogspot.com/2009/04/bragging.html:

An Open Discussion for Gifted Education: Bragging

When is it okay to brag about being super smart?

I get aggravated at some of the really smart kids at our school because they don't want anyone to know they are smart.  I've had discussions about it both privately and individually when it hit me a few years back, I tend to hide my smartness myself in order to get along with other people.

Let's face it, I teach computer science, when it comes to technology I am the smartest person in the room.

So I make a concentrated effort to model proper "smartest person" in the room behavior. Being helpful, and demonstrating cool technology stuff to as many people as I can when I am NOT in my room.

I also model good sports bragging behavior, as I am an active participant in dog agility.  I do this by displaying my ribbons and sharing my accomplishments with people who are interested in such things.

I think modeling behavior is very effective with students -- though it takes a long time for it to have an effect.