I Know This - You say this when you want to act like you know exactly what

You say this when you want to act like you know exactly what the other person is saying. Usually said with extra loudness and a lot of attitude.

"I know this!" he said, right after his teacher explained the lesson again.

"I know this!" she yelled, when her friend said something stupid.

"I know this!" he said, after his friend asked the same question for the 10th time.