He's talking about 19 year old WTA player Donna Vekic for those who weren't aware. She's played mixed doubles with Kokkinakis and is now dating Wawrinka.
This guy is going to end up getting bashed and/or booted off the Tour at the rate he's going.
After he lost the first set earlier today, Kyrgios said this to Stan without realising the courtside microphone picked it up and televised it worldwide. Wawrinka confronted Kyrgios in the locker room saying that Kyrgios tried to avoid him but that he wouldn't reveal the details of what he said to him. Stan also called for the ATP to take action against him because he said it's not just about what Nick said today but that "every match he has problems, every match he behaves badly and on top of that the problem is that he doesn’t just behave badly towards himself he behaves very badly towards the people around: the other players, the ball kids, the umpires.I really hope the ATP will take major action against him this time."
Then jumped on Twitter (from the bottom up):
Nick's buddy Aza
Nick's response + video of him saying it: http://www.sportsnet.ca/tennis/roger...with-wawrinka/