He thinks that's funny.
Because he knows how angry anyone not on his team gets when he does stuff like this, but also knows nothing can be done by the other team to stop him.
So it's him winning one in his head.
He won't stop until no one cares. That's worse but healthier.
Where's SNL when we need them?
They have the unique ability to piss him off without him being able to retaliate.