Party ideas ? ? Please help ! 10 pointss?

Ok so I'm having a little sixteenth birthday party in a park. Its gonna be like 80. But the problem is that I'm not sure what type of entertainment I should have and I don't really have that many choices. The park has a spray water area so I was thinking we could all get wet and stuff , do you think that's like too babyish or weird for a birthday party ? Like my friends actually want to get wet because all my friends are like childish and Fun lol. And for the food I'm serving rice and chicken and pasta and chips and soda . Is that good ? Cause I don't really know what else to serve. I'm gonna have about 15 people and I can't do a barbecue because it just Gonna be me and my friend ms there and that's too much work. I was thinking like having a dessert competion. Everyone has to bring in their fav dessert but I'm not sure :/ Please Heelp .. Thanks !