Holding a 18 years birthdapary, how?

So, getting 18 in the end of the month and was thinking about actually holding a real birthday party and invite some friends since I've not held more than one when I was something like 6-8 years old. My idea is to have Smörgåstårta (look it up on google images) and Strawberry Juice for the celebration, but what could I do apart from that... feels a bit empty to only eat some food and then end it there. Any activities etc?

EDIT: WOW, what happened to the title? It was supposed to be "Birthday Party" but I probably read it to quick to realise. Requesting mod to fix if posible. :)

EDIT 2: Wow, blackout one hour after I posted this. Went to sleep with lack of internet so couldn't respond. Sorry for breaking a rule...