A free CDN service for your WordPress site is not a hoax, here is a way to host the images you upload to your posts or pages and without paying a dime more. The solution is a WordPress plugin called:

A free CDN service for your images

Jetpack is a plugin developed by Automattic the company behind WordPress. This plugin will enable some features available for users using the self hosted version at WordPress.com. One of this features is Photon, when enabled it will upload your photos to WordPress.com CDN and will be served from there. This is done without any further integration, or configuration on your site.

So to have a free CDN for your WordPress images, just go ahead and install Jetpack and activate Photon, your images will be delivered blazing fast!