You will sometimes be given an option to watch an advertisement video to give yourself a boost. This can happen after you crash or reach at the end of a level. Agree to watch the video, and when it appears, select the "X" button at the top right corner. This will close the advertisement, but you will still get the bonus. Do this at every opportunity, especially at the end of a level where you can double your total coins. Note: Some ads will play automatically.