When your are in a picture with a hot girl, only to find out she or someone else has cropped you out of it; most of the time to make it a more appealing facebook default. Usually a limb or portion of your face still remains in the photo, letting everyone know you weren't important enough to be kept in it
Someone Who Is At A Convention Where People Dress Up As Characters From Anime, Movies, TV Series, Or Other Fictional Characters And Steals All The Attention From You Trying To Show Off Your Amazing Cosplay Outfit And Looks In Said Outfit Even Though You Look The Part Perfectly!
Everyone Was Watching Tym Dressed As Dante Instead Of Trent Dressed As Virgil
At Ohayocon 2012. Trent Pushed Tym And Said, "You Cosblocker!"
The New Dante Stole All Of The Attention From The Old Dantes At Ohayocon, He Cosblocked The Entire Day. Stealing The Attention From All Other Cosplayers.