Outdoor or rowdy games would be Chair Game, Death Ball, Sardines, or Steal the Bacon (explanations below)

Chair Game: Everyone links hands to form a circle around a chair. Players try to force the other players into touching the chair. If any part of person’s body touches the chair, they’re out. Last person left is the winner.

Death Ball: Everyone stands inside the circle touching the chair "wall." Someone drops the ball(s) in the center of the circle. No one is allowed to move away from the wall until the ball(s) bounce three times. If someone stops touching the wall before then, they are out of the game for that round.
Once the ball(s) have bounced three times the players begin trying to hit the ball(s) at each other using only their fists. If the ball touches a person anywhere on their body besides their fists, they’re out. If someone hits a ball out of the circle, (directly or indirectly) they’re out. (If someone hits a ball at someone and it bounces off of them and out of the circle, both the person hitting the ball and the person who got hit are out.)
Players are allowed to dribble a ball (or two) like a basketball if they use only their fists. Players are not allowed to hold the ball(s) or use the palms of their fists. If they do either of these they are out for that round.
Once players are out, their job is to round up balls that have been hit out of the circle and toss them back in. Players are not out if they are hit by a ball coming from the outside of the circle.
The last person left in the circle wins. The winner of a round starts the next one by dropping the ball(s) in the middle of the circle.

I’m running out of room so here:
http://lds.about.com/library/bl/games/blsardines.htm
http://www.ldssplash.com/familyfun/outdoor/Steal%20the%20Bacon.htm
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I’m 14 and have several siblings. I know how to have fun with kids ages 5-16. And other ages

you could pair up in partners and have a treasure hunt, i know it sounds a bit childish but if you like have to do things along the way like try to work out riddles or do eachothers hair a certain way, they are really fun.
Also you could have a kareoke competition and have some of the parents be the judges.?
You could also have relay races in the pool, hair and make-up styling and again parents could be judges.
There are heaps of things, just use your imaginaton:)

Happy 11th birthday and hope you have fun
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Marco Polo

Well with you that makes 6…so you can play team games, like water volley ball…3 against 3

water balloon fights are fun
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Pass the parcel
Musical Chairs
Musical Statues
Get a Piniata
Scavenger Hunt
Lolly Hunt
This game where everyone gets a baloon tied to their ankle, and everyone goes around trying to pop others baloons while protecting their own … last baloon alive wins!

Hope I Helped!
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Hope this helps. (:
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