The first time that they made love it was Valentine's day. That was the first time that Sakura had seen Kakashi without a mask, and also the first time that Kakashi (VERY happily) saw Sakura naked. It was the first time that she saw Kakashi's full smile and laugh, and unfortunately it was also the first time that she saw that laugh directed at her. Even more unfortunately, it was because of the first time that Kakashi heard one of Sakura's bodily functions, otherwise known as a squelch!
It was the first time that he saw that shade of a blush as a result, and he loved it.
Squelch!