I hate when the pros shout "C'mon!" at a ball their opponent has hit that's going out, especially when they pump their fist afterward. It is mostly (but not exclusively) the women who do this. Sharapova and Safina are major offenders, and we can now add Goerges to the list. I have seen Federer do it several times too. This seems to me to be the height of bad manners and poor sportsmanship. They are cheering that their opponent has made an error. It does show, however, how insecure they are feeling at the moment to stoop that low.