I was playing a challenge match earlier and was serving 30-15. I toss up the ball and the opposing team is yelling "wait!" I look around for any people or balls behind me. Nothing. I go to toss again and they yell "wait!" They point to my partner (whom I've never played with). He is literally chatting on his effin cell phone right on court during a game! For some I could forgive this mortal sin (emergency room doctor for example). After 15-20 seconds, he hangs up and surreptitiously slips the cell phone back into his pocket like nothing's wrong and nobody noticed... we didn't even receive an apology for waiting. I was ready to end the set right there and walk off the court. I've never experienced anyone approaching this level of rude behavior on a tennis court.