There are lots of different ways to tease a girl, and it all depends on what sort of response you're hoping to get from her. If you want to make her laugh, you might say something like, "I bet you look great in those yoga pants." Or, if you're trying to be a little more flirty, you could try, "I bet you taste as sweet as your favorite candy." Ultimately, it's all about reading the situation and knowing what will work best with the girl you're talking to.