Commonly, you don’t tuck your ears into a snapback. Ideally, the fit of the hat should be snug, so there’s no room for your ears, and the correct size will generally sit higher than ear level. Once again, however, it comes down to personal preference. If you want to protect the tips of your ears from sun damage, tucking them into the hat will help (but still wear sunscreen). It also comes down to the shape of your ears. Some people can be self-conscious about ears that stick out too much, and tucking them in can help hide them.