This is neither a commentary on 'Deez' jokes themselves nor on the appropriateness of an NFL coordinator using them publicly to combat an embittered fan.
It's simply a statement of fact: Washington Commanders defensive coordinator Jack Del Rio responded to a fan's complaint of him by telling that fan to "Bite deez."

The fan specifically called out Del Rio, head coach Ron Rivera and team president Jason Wright for allegedly "playing games" with defensive lineman Daron Payne, which the Twitter user professed will result in them all being bitten by karma when Payne "goes within the division."
To which Del Rio replied, "Bite deez."
Now, if you don't know the punchline to deez jokes, I strongly suggest asking a stranger on Twitter. I'm sure they'll be more than happy to fill you in.
And that's all I have to say about deez.