Ethan can be quite the giggle monster. You never know what will cause him to erupt into laughter.
I love love love listening to him laugh. While he finds the simplest things amusing, the problem is that it only works once. One day a new funny face or funny noise is the height of hilarity but if you try the same trick again he just gives you a bored look that clearly states he's seen it all before and that you need to try harder. So while you have to work at those giggles, it's just the happiest sound for me to hear.
The other day we blew a tissue at him and he literally laughed for an hour straight - he laughed so hard he even did a mini snort.