The NBA has always had intense rivalries. Wilt vs. Russell. Bird vs. Magic. Jordan vs. Isaiah. Kobe vs. Shaq (just kidding).
One of the nastiest one-on-one rivalries of all was between Larry Bird and Bill Laimbeer. Those guys really disliked each other. Some guys unquestionably got under Bird’s skin. He famously had a big fight with Julius Erving where they each had his hand on the other’s throat, and also got into a heated confrontation with the great Kareem Abdul-Jabbar.
With both though he respected them immensely and Jabbar later said that Bird was the toughest player he ever encountered. As for Erving, they shook hands the next game and made up.
That never happened between Laimbeer and Bird and probably never will.
Bird regarded Laimbeer - rightly - as a dirty player. And when Laimbeer took Bird down in the 1987 playoffs, Bird was enraged. He came up swinging and, after they were separated, fired the basketball at Laimbeer’s head (Robert Parish paid Laimbeer back in the next game as you’ll see).
Neither guy has relented in the slightest since.