Why do guys tell pretty girls they're ugly?

Anonymous
A guy used to call me ugly all the time. I'm pretty sure he was joking, because he's my friend and he's the type of person that likes to joke around a lot. But then again I'm not sure if he was joking, because I've seen guys tell girls they're ugly and meant it. I'm just not sure. He's usually nice to me and talks to me when he gets the chance, but I guess that doesn't mean he thinks I'm pretty either. I guess I'm just wondering if a guy will tell a girl she's ugly if he really thinks it or if he will jokingly call a girl ugly even if he really thinks she's pretty.
Why do guys tell pretty girls they're ugly?
7 Opinion