jolliness — in good spirits; lively; merry: In a moment he was as jolly as ever.
joviality — the state or quality of being jovial; merriment; jollity.
gaiety — the state of being joyous, vivacious, or cheerful.
blowout — A blowout is a large meal, often a celebration with family or friends, at which people may eat too much.
celebration — A celebration is a special enjoyable event that people organize because something pleasant has happened or because it is someone's birthday or anniversary.
conviviality — friendly; agreeable: a convivial atmosphere.
festival — a day or time of religious or other celebration, marked by feasting, ceremonies, or other observances: the festival of Christmas; a Roman festival.