My bday turning 15, what should I do to celebrate?

Ok my 15th bday is in september
Me and my sister were born on the same day but im 2 years older so shes going to be 13
Any ideas for our bday party?

Giant picnic at the park, then play freeze tag. Or a pool party might be fun too.

What I did for mine was invite a couple of close friends
Go out to a nice resturant then after rent a limo to pick up your friends from the resturant roll around for a couple of hrs and then have ya'll parents reserve ya'll a hotel. I know it may seem like much but try and see.

when I turned 15, I had all my friends come to my house and we all dressed up in hula skirts and my aunt came and picked one person to sit on a chair and do everyhting she did , say some weird things, stand up, do some weird hand flow stuff, (while they are standing put a wet sponge on their chair), and she had them scream somethign and and sit on the chair very hard and they will realize there butt is VERY wet. it was hilarious. I also had a beach party in my backyard and did kareoke and slip and slide when I turned 13... but you can just do the basic dance/pool party. HAVE FUN!!

thanks ya'll
thats perfect because I live right next to a lake