"Derp" applies when a character's eyes are pointing in two different directions at once, and is generally behaving in a silly or foolish manner.
When you upload, you may get a "File Not Found" Error. We are currently contacting our web admin in order to fix the issue, but until then, we have a work-around that has proven to work for the time being. If you wish to upload, please save the image to your computer, then add it to the upload screen through the "Browse" button. We hope that works for now and will make a notification when the issue is fixed.