Blackhat SEO (Search Engine Optimization) is a type of rule breaking of google's search engine optimization. Using this trick you can make your website to be shown at first page in Google Search Engine; however if caught by Google, your site will be blocked by google forever.
BlackHat SEO will show your website in first page for one day, and then you will be in trouble because Google will caught how come your site got much popularity to reach first page?
Next if you missed to keep your site on first page by some reason, Google system will alert that your page ranking was fake.
Keep yourself out of this trouble and do not use Blackhat SEO.