SPUD
Always played this as a kid. We enjoyed it, but it took on a new meaning at 11:00 on night after partying all day when I was a bit older.
Everyone's assigned a number, 1 to however-many-people, in numerical order. #1 starts with the ball in the middle of the yard with everyone around him in a circle. #1 throws it high (as high and straight up as they can) in the air and yells a number. Everyone else runs away as fast as they can. If the person who's number is called catches it, they throw it back in the air and call another number (so don't run away too far at first!). This repeats until the ball hits the ground. Everyone must freeze. The person that didn't catch the ball can take three giant steps towards someone and has to hit them with the ball. The person being thrown at can dodge the ball, but must keep their feet planted. Like I said, fun game for kids, but still enjoyable with a bunch of over-partied adults!
Full-Contact Spoons
Just like the game of "Spoons" you'd play around the kitchen table,
http://en.wikipedia.org/wiki/Spoons, except you play outside, throw the spoons in the yard about 10 yards away from the group, and have at it. Can get ugly.
Beer croquet
Just like regular croquet, except when you finish your beer, you can throw the empty can (bottles can cause and have caused injuries) anywhere you want from where you're standing when you finish it, creating a few dozen obstacles by the end of the game. You can't physically touch the cans, but can attempt to move one with your ball. You can clear the field after each game, or leave them for a real mess after a few games. We say you must throw the can more than 5 feet or so and no sandbagging just so you can wait until you're right by a gate to throw it to block a gate. One summer weekend in my college days, we played all day at my parents house. Let's just say Mom wasn't to thrilled about how many beers 10 guys can drink in an afternoon while playing croquet. Damn-near needed a bobcat to clean up the yard. Made for a loooong final game, too.
Like all backyard games, rules may vary! Just be fair, don't argue about it, and have fun!
Edited by Mo-Problems, 09 March 2012 - 08:19 AM.