I posted this in a recent thread that had a user asking. I figured I will post this in the How To forum for people wanting to know how! Hope it helps.
Use http://imgur.com to upload your image. Once uploaded you will have a bunch of links in regards to that photo. Like this
You want to use "Direct Link (email & IM)" as the link you use to upload. Once you have copied that link you then paste it into the chat field by clicking the Insert Image button
Then click on the "From URL" Tab and paste the link you copied from "Direct Link (email & IM)" on Imgur and make sure the "Retrieve remote file and reference locally" is unchecked.