At USO he almost got into a fight with German Pohmann, called him Hitler. Another time at USO, in an infamous match with McEnroe, the umpire Frank Hammond disqualified him, but, as a riot rose among the crowd, the decision was corrected by the tournament referee Talbert.
Urban is right, as usual. In the first match, Nastase got particularly ugly. He beat the German and when the German refused to shake hands after the match, the crowd began to vent on Nastase. Nastase's response was to spit a mouthful of his courtside orange drink back at the crowd.
In the second match, I believe at the 1979 US Open, he and McEnroe did get into it. The match started late and the crowd, in anticipation, was fairly well lubricated with whatever beer they served back then. Frank Hammond was one of the most respected umpires around back then and if I remember right, one of the few professional umpires. He DQ'd Nastase and the crowd went ballistic. If I remember right, McEnroe had, typically, lost the crowd by trying to hit Nastase. Of course, Nastase acted like he'd done nothing. But, when the match started to turn against him, Nastase began questioning every call in fairly graphic terms. I think that match ended after midnight.
There are tons of more examples. One of my favorites was when Nastase was playing a US claycourt event in preparation of the US Open. The match was to be televised and he was given a pre-match briefing by the TV folks. They pleaded with him to not use any vulgar language or gestures. They almost got what they wanted. Nastase agreed to be a good boy. His opponent that day was an Italian whose name I can't remember. Nastase made good on his promise, he didn't use any vulgarities in English, rather saying what he had to say in Italian for the benefit of his opponent. Nastase also used an Italian version of the finger during the match which finally sent his opponent over the edge.
During the whole match, Nastase's behavior and demeanor toward the English-speaking American crowd was light and playful. He smiled and acted like nothing out of the ordinary was going on.
There were two players who bothered Nastase. Those two were Stan Smith and Bjorn Borg. The reason they bothered him was that neither ever reacted to any of Nastase's antics. It got into Nastase's head that he couldn't get into theirs. I remember once, Nastase was getting his clock cleaned against Borg. In desparation, Nastase stood facing Borg, spread his legs, and dropped two balls from behind his back. Borg hadn't seen that before, apparently, and smiled. Then, Borg went back to beating Nastase's brains out.
Nastase's biggest weapons IMO, outside of his physical prowess, were his anticipation and unpredictability. He seemed to know where the other guy was hitting and had the uncanny ability to hit a shot that his opponent couldn't predict. Nastase was the first player I ever heard of who hit topspin lobs off forehand and backhand and on the dead run.
His most famous shot was the Bucharest Backfire as named by Bud Collins. When lobbed, Nastase would run back and with his back to the net, hit an over the shoulder overhead usually back past his opponent, with a wood racket. Nastase could also volley from anywhere around his body, between the legs, behind his back, over his left shoulder with his arm behind his head (at least that's all I saw).
The guy had incredible talent and phsyical ability.