Haha, that's Griff's OC, Fisk, and I don't think its a costume... though I'd have to ask.
And just as a side-note, if you don't know Griffsnuff, I cannot recommend enough that you check out her page,
she is beyond any shadow of a doubt one of the most talented people on this, or any website dedicated to art.
She's unique in every way, and I honestly adore her, and her work. ^_^
Simply put, she's incredible.