When you swing your penis up and down so it goes between your legs. When it goes between your legs it
will reach between your ass cheeks and your ass cheeks
will clench on your penis and you
will pull it out rubbing along the taint eventually leading to ejaculation. Right before your penis gets clenched between your ass cheeks it makes a huge clap noise upon impact so you are essentially clapping your cheeks. This works best with shit stains in your ass cheeks, they
work as a lubricant.