Punkie Night. There's this strange feeling of seeing owlets "trick-or-treating" for sweets by singing songs and stuff that makes you laugh and say "Awww!" at the same time. Then there's Blooking For Berries (which is definitely Bobbing For Apples), and the tricks they pull on other older owls. One example is putting honey in their nests so that it messes up their feathers. Otulissa is not amused.
Bonus points since this Ga'Hoolian holiday is a mix of Halloween and April Fool's.