Step 1) Go to: http://imgbox.com/
Step 2) Hit "SELECT FILES" (surprise surprise)
Step 3) Hit "Content Type" and choose either Family Safe Content or Adult Content and hit "START UPLOAD"
(no need to bother with anything else)
Step 4) Hit the "Copy" button next to "Links Only"
Step 5) Paste into the Facebook comment box and bippity boppity boo, DONE!!! :D
EDIT: Well it's now August 2013 and it seems FB have added a "photo comment" button anyway so bollox :/
Not that it really matters coz i deactivated yonks ago. . . . HA!!!