^ Probably because you've already got the picture cached. Your link to the picture didn't work either until I took all that "?sttoken=...." stuff out of the link.
Edit: OK. I think I figured it out. What you need is the link as you posted it, with the ?sstoken= part of the URL removed, then add .jpg at the end and wrap it all in the open/close img tags:
http://ppl.ug/3dmmtgs5jl0/pv/8zs6MY6GRA ... sGGJtX.jpg
" onclick="window.open(this.href);return false;
The only question I have left is how you got it to serve you the token information. It's pretty clear that's the actual information for the .jpg. But I've tried a couple of different browsers now and can only get it to serve the URL as the OP posted it.