The first rule of Movie Babysitting: Do not take your charges on any unplanned nighttime activities. The second rule of Movie Babysitting: When you inevitably do take your charges out into the wild, make sure they are not dressed in store-bought Spider-Man costumes, because when the kids run away and team up with a recently dumped high-school student to break some laws in the name of love, it will be virtually impossible to distinguish them from the other Spideys. So Victoria Justice learns in Fun Size, which sends the breakout Disney Channel star running around suburbia in a Dorothy costume (always bring a change of clothes!) while befriending nerds and battling neon-chickens. It’s like she — or Gossip Girl creator Josh Schwartz, making his directing debut — missed all the crucial lessons at One Crazy Night Survival School. Don’t cut class, kids! It’s too important.