This wasnt intended to be evil. But the fact that it kind of came out that way made it so much better.
My friend and I, lets call him Gavin, are digital artists and it was going to be our first time exhibiting at Comic Con. It was a big deal and we were both quite anxious about it, but Gavin couldn't get off work the day before the convention to check that everything was set up properly. The convention usually provides you a booth with your name in big white letters above your head and a table for you to sell your art prints from. I told him not to worry about it because I would be there and I would be able to let him know if anything was wrong.
On setup day, my fianceé comes with me to help set up my booth. It's really awesome to see your name in big letters at a convention like that so we were taking lots of photos. But when we came to Gavin's booth I thought it would be funny if we made it look like they screwed up his name. So i told my fianceé to point and laugh at it while I took a photo,then I could edit the photo later.
So at home I quickly erase Gavin's surname in Photoshop and try to think of something to replace it with. I thought it would be too cruel just to put a spelling mistake in because then it would be actually believable and it might stress him out before the big day. So i put what I THOUGHT would be obviously fake, so that when he saw it he knew i was just messing with him. So I erased his name and just wrote "POTATOES". So his booth now read "GAVIN POTATOES" in big white letters. I managed to match the font perfectly and with my fianceé actually in the pic reacting to it, it really did look quite good.
So that evening I send a message in our friends group saying "Gav, sorry man, I didn't know how to tell you and its too late to fix it now. But they screwed up your name..." I waited a bit then sent the photo. The idea was to get him to panic a short while and then see the obviously fake photo and know i was just messing with him. Anyway I found out later that it didnt go as planned. He said he was driving when i sent the photo and he only had a chance to glance at it. So with my fiancee in the pic laughing at GAVIN POTATOES above his booth it really looked believable. So he was just going "WHAT THE F*****CK" on the way home.
So long story short we all call him Gavin Potatoes now.