Guys that think they're God's Gifts to Girls

A while ago I was talking with a few girls and we got onto the topic of a guy we all know.

He's an alright guy- tall, relatively academically smart and has his drivers licence.
But he thinks he's really good. To the point that it's not self-confidence but ARROGANCE!

Those kind of guys really reeeeally REALLY annoy me. Heck, I always try to bring down his ego by a few notches but I don't think it works at all. He think he's all that, going around saying 'I heard you girls said this and that about me,' when the girls just think he's a complete dork.

I don't really understand why girls would like those kind of guys

And they're the kind of guys who go after two girls at once without them knowing about the other. One rejects them so then move to the other and vice-versa. It's so sad!!

I don't get why guys would want to have TWO girls when they can get together with ONE really amazing girl and keep her by not doing anything stupid like say... GOING AFTER ANOTHER GIRL?

Perhaps they feel insignificant amongst other guys or they think that it's too 'normal' to just have one girl? Is it so hard to ask guys to keep their eyes on ONE girl and ONE girl only?