Type anything(alphabetical characters) and scratchy will say it. Since scratch has no 'Key Backspace Pressed' block, you will need to press the left arrow key instead. Press the down arrow key to clear all. Also, if you want an exclamation mark then press: '1' and the up arrow key Also, don't type too fast or some letters may be missed out
This method could be altered to be used in animations as to seem when a character is speaking, it could have the effect of typing