So, how are you going to celebrate? Suggested forms of celebration include food, fireworks, dancing and much merriment!
As to the, "Why should I celebrate Hobbit Day?" Well, if I need to answer that for you, maybe you shouldn't celebrate it!
For me, I'm just enjoying Tolkien today, they man was a genius with words and an expert storyteller. So, I will leave you with some of his thoughts...
“We have come from God, and inevitably the myths woven by us, though they contain error, will also reflect a splintered fragment of the true light, the eternal truth that is with God. Indeed only by myth-making, only by becoming 'sub-creator' and inventing stories, can Man aspire to the state of perfection that he knew before the Fall. Our myths may be misguided, but they steer however shakily towards the true harbour, while materialistic 'progress' leads only to a yawning abyss and the Iron Crown of the power of evil.” ― J.R.R. Tolkien