This is a truly bizarre two minutes of video. At the end of a spirited rally in third-set action at the Winnetka Challenger, Alex Bogomolov, Jr. calmly quits the match and tells the chair umpire to go fuck himself.
It looks like Bogomolov let up on the final shot at his feet on the baseline because he believed it was called out; the commentators indicated that the call may have come from someone in the stands. The chair umpire informed Bogomolov that it was just off the line, the line judge had seen it just as he had, to which Bogomolov promptly offered his hand and conceded the match. His opponent's face at 1:02 says it all.