COMMUNITY BUILDING 151. Celebrate Half–Holidays Have “Holiday” parties six months from their actual date: Halloween in April, an indoor luau in December. Alternatively, you can also celebrate half–birthdays (the date six months before/after someone’s actual birthday). Here are the dates for some good Half–Holidays: Half 4th of July – January 4th Half Halloween – April 30th Half Thanksgiving – 4th Thursday of May Half St. Patrick’s Day – September 17th Half Start of Summer – December 22nd 85