What does this hand gesture (probably an insult) mean?
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/382756_184457981651147_100002608396025_324118_918422926_n.jpg
Okay, the guys in my web development class have been doing this as a joke and I know that it's some sort of insult (I think) but I'd like to know what it actually means :P thanks