Get wild this Halloween and bring your boys and “ghouls” to trick-or-treat at the wildest neighborhood in town. A spooky (but not too scary) Halloween adventure is planned at this 21st annual HallowZOOeen, which celebrates its opening night tonight. Get treats at Goblin Stops, play games and see zoo mascots as you roam the trick-or-treat trail, and don't forget about the haunted train rides. General admission is $7 (or $6 for members), and kids under 2 who are not trick-or-treating will be admitted free.