If you find @Joeydale13 at GamesFest, who will be dressed up as Commander Shepard, take a photo with him, and tweet it to @EA_ActionMan for a chance to win a Mass Effect N7 t-shirt.
It is the t-shirt pictured in EA_ActionMan's and Joeydale13's profile, which is also available for purchase at the BioWare Store (verified by Joeydale13). The original tweet:
Greetings all - @Joeydale13 is becoming Commander Shepard at #GAMEfest if u see him get a photo & tweet at me 4 chance 2 win an #n7 tee
Here's a quick photoshopped illustration, as I don't have any in-costume photos of Joe Dale to use: