Kids love to dress up and have fun with their buddies.
A Mardi Gras party would let them do both, while celebrating Timmy's seventh. Many schools have policies regarding parties and some schools do not even allow parties. Ask the teacher how much time you would be able to take out of the regular class schedule to hold the party. This will definitely make things easier when you are planning activities. In New Orleans teachers typically ask students to bring a shoe box in from home and decorate it, representing a traditional float.