NEW: President Trump roasts RFK Jr. with a joke about what's on the WHCA Dinner menu with a call back to the many controversies surrounding the HHS secretary an

NEW: President Trump roasts RFK Jr. with a joke about what's on the WHCA Dinner menu with a call back to the many controversies surrounding the HHS secretary and wild animals: "I want you all to know that Bobby Kennedy, who's right here personally, ran over the cow with his car." “He cut it up and…