This is what happens when a guy asks a girl out (for a dance or
something) when she is already taken, but the girl likes the guy who just asked her out. She tells
this guy no, but makes in obvious that she is
interested.
Harry Potter (very quickly): Cho
would you like to go to the Yule ball with me?
Cho: Oh, I'm sorry, but I've already been asked ... and I kinda said yes...
Harry (akwardly): Oh ok, fine, good,
that's great (then turns around)
Cho: Harry! But I REALLY am sorry!
^now that's what cho-changin is