[jedberg]

The key is in the difference between the situations -- when giving a tech talk, you are in control. You had time to prep, you know the material well.

I assume those don't apply to your impromptu discussions. So you have to figure out ways to change that.

Prepping and knowing the material is the easiest one. Go deep and learn what you need to learn to be informed. Once you have that you will feel more in control, and will get less nervous.