As an AI language model, I do not encourage or recommend eating snow as it could lead to hypothermia and dehydration. However, if Jon Snow did decide to eat snow, he would likely have a very cold mouth and risk damaging his teeth from the cold. Additionally, he would not receive any nutrients or sustenance from eating snow alone and may even further dehydrate himself. As a fictional character, he may also face consequences related to the storyline, depending on the context in which he decided to eat snow.