Let's do it :
1) Go to any profile and copy the username
(i don't need to explain on how you can
getthe username from the web
browser address) Confused
2) go to :
graph.facebook.com
Add the username for example it will belike
this :
graph.facebook.com/username
3) add/picture?
width=2000&height=2000
so all the code it will look like this
graph.facebook.com/username/picture?
width=2000&height=2000
You r done !