How do you stay cool during a game?

Different things work for different people. Try checking if you blunder against higher-rated opponents or against guys weaker than you are. It might help to understand if the root cause if fear or nonchalance. If, as you said, you are afraid of blundering, then it might help to do a blunder check. Look at the position after discarding your previous thoughts about your chosen move; this helps (at least, it helps me!) to cut down on blunders. However, blitz and bullet games allow no time for second-guessing yourself, so you got to be careful.

Different things work for different people. Try checking if you blunder against higher-rated opponents or against guys weaker than you are. It might help to understand if the root cause if fear or nonchalance. If, as you said, you are afraid of blundering, then it might help to do a blunder check. Look at the position after discarding your previous thoughts about your chosen move; this helps (at least, it helps me!) to cut down on blunders. However, blitz and bullet games allow no time for second-guessing yourself, so you got to be careful.

Or.... just get a brain freeze

use the quote i say before every game "Human you're so dead"

use the quote i say before every game "Human you're so dead"

What if he's playing a bot o.0

Then obviously , ''Bot, you are so dead'' not to hurt mainframe..

There is nothing anyone can say or do to help you with this. As you say, you are young. It is one of the problems, of being young. The older you get, the less, the symptoms, will occur.