The reason why idols tweet is because they want their fans to become crazy, don't you think? PD-nims are not idols but some of them tweet with idols and we, the fans, follow them just because our idol follows them. Sometimes, PD-nims wants fun too, sometimes they wants to be popular as well as idols are. And the fans are there to make them happy. PD-nims are also pretty. If they are not on stage, that doesn't mean they're not pretty or cute, because they are.