Okay.
Sounds like you got killed by your own adrenaline. Has happened to the best of us, usually in situations in which we are caught by surprise.
You get the amount of adrenaline normally required for a fight, shot right into your brain and body. This makes you nervous, shaky, increases your heartrate, and as this happens, you start to feel concious of the process going on. Now, your mind can't make the adrenaline go away all of a sudden, so it has to go somewhere, and it has to be channeled. But instead of channeling it, you try to make it go away. You sit there, waiting until the rush of adrenaline goes away and you say stupid things.
It's my personal theory, that experience and confidence are gained when you learn to channel these hormonal rushes, into something you can use, and when we learn to control it more.
Just an example; has anybody here ever had a presentation training? Many of you probably have.
Most people tend to be nervous the first time they give a presentation. Whether they want it or not. This nervousness, actually has a purpose. The hormones sent into your brain, are saying that you need to increase your focus, increase your energy and put you into a higher state of alertness.
What most people do wrong, is that they fight this rush. Instead, people should realize that that rush, is in fact a very useful tool. Once you learn how to control it, it will allow you to give great presentations. People who don't have this, tend to give rather boring presentations!
The basic message I'm trying to get across here is this: as you become more experienced, you will get more control over these hormonal rushes, your body will dose them more properly, and you will learn to use them for your own benefit, making them work for you instead of against you.