The whole “Go Nads” thing has been done before; see, for example, this “Let’s Go Nads” t-shirt that was once shown on a MASN telecast.
I didn’t find that particularly hilarious. And making the slogan way bigger doesn’t necessarily make it any funnier. Plus, the team is actually called “The Nationals,” aka “The Nats,” and not “The Nadionals,” aka “The Nads.”
But I guess someone must think this is amusing.