My 3yr old son had decided that he wanted a marine corp birthday party.  We had to actually use GI Joe party supplies that I got from partyetc.com  I got a camouflage jeep piñata from birthdayexpress. com On the invitations for location I put Ventura Military Base, for the time I put 1100-1300 hours, for RSVP I put contact base commander.  On the invitation I also put wear your camouflage and be prepared for battle.  When each child arrived we painted their faces with black and green paint. We also had a obstacle course set up and as the kids went through it they bombed with water balloons. We even had camouflage table cloth and crepe paper.  For the cake I got candles for birthdayexpress.com that looked like toy soldiers and tanks.  I used graham cracker crust to make a sand hill on the cake.  We had jungle juice to drink(lime Kool-Aid).  Frozen ice cubes with raisons in them so it looked like flies floating in their jungle juice. All the kids had a blast.  What was also cute was that the girls wore pink camouflage. The camouflage outfits were inexpensive at Wal-Mart.