This can go one of two ways. Give the Perfect Gift Bags Make every child feel like a superhero by including gift bag items such as a bat mask and a super hero cape. Let each child choose which side they want to be a part of, set physical boundaries, and let their batman and joker birthday party run batman and joker birthday party. There are tons of printables available to you on the internet. Make your little superhero feel extra special this birthday with a theme everyone will love—LEGO Batman. The Bad Guys This one is just as it sounds. Then, hand out squirt guns to all the kids to use in an effort to unfreeze Batman as fast as they can. As you may have guessed, anything relating to bats goes with this theme.