That's an adidas "Geek Up T-Shirt," and it'll only cost you $31.95. The beard is a nice touch.
There's also this, for $33.95:
Now, if the Knicks could put this on a shirt, I'd be interested.
So, this is happening. pic.twitter.com/DNurev0w6w
— Howard Beck (@HowardBeck) March 18, 2014