Before the birthday party, make enough certificates so that each guest will get one.
Have different categories like best vocals, best stage presence, best choreography, best superstar look, funniest performance, etc.
Also once you know who will be attending, make a list of the order of performers.
This will help you set up the background music ahead of time and help your host know who is performing next.
The list should include the performer's name (real name or stage name), the song they will be performing and the musician who originally did the song.
Let the party guests know ahead of time that there will be an American Idol contest to discover the next American Idol. That way they can choose their songs and practice ahead of time if they want.
Also let them know that they can come in costume if they want. This way the guests may show up to the birthday party as the "superstar" that they will be performing as.
If you want, have some "extra" costume props on hand for those who don't dress up but get in the mood later. Good ideas are silly sunglasses from the dollar store, wacky hats, feather boa's, scarves, and anything with stars on it.
Let the guests do a duet if they want. This helps with anyone who is shy and doesn't want to perform by themselves. Also allow them to opt out and be "back-up dancers" if they're really, really shy and just don't want to do it. Put this in the birthday invitation ahead of time so people can r.s.v.p. as a performer, back-up dancer, duet or as the host.
You will want to have 3 judges. They can be guests that don't want to sing. For extra fun have the judges dress up as their favorite American Idol judge and impersonate them during the performance.
Set up a table for the judges with a tablecloth on it to give it an "official air". If you don't have room for that, the judges can sit lined up on the couch.
They should have a pen and notebook each so they can take notes. They also should each have a copy of the list of performers so they know who is singing what song. This will help in case they don't recognize a song as it is performed.
It's best to designate a "host" for the contest. That way they will be able to keep the event going as planned without the judges having to chime in. They can announce the next act and ask questions of each contestant after they perform, just like on the tv show.
If there is one party guest in particular who is the "class clown" ask them ahead of time if they would be willing to be the host. Give them a copy of the list of the order of performers, so they know who to call up next.
You'll need one person to act as a "behind the scenes technician". They'll get the music queued for each act. They'll also need a list of the order of performers so they know which song to put on next.
Ideally have all of the party guests say what song they will be singing in their r.s.v.p. for the party. That way the technician (most likely a parent!) will have time to set up the music before the party begins.
Have the contest set up for an hour or two into the birthday party. That way late-arrivers won't miss out. It will also give everyone time to dig through the props bin and get their finishing touches on their costumes. Have a fun sign up on display that states what time the contest will begin. That will build "buzz and excitement" around the event.
It's time for the contest! Play the American Idol theme music to the tv show. When it's done make an announcement that the contest is starting. Have all the judges get seated and have all the contestants lined up on one side of the room. Ideally the contestants should be lined up in the order that they will be performing.
Have your "host" announce that after the contest there is going to be a brief intermission followed by a "Red Carpet Awards Party" and an "All Stars Banquet".
Have the host call up each act for their performance. The host should ask a few silly questions of each contestant just like Ryan Seacrest does on the show. Then they should direct the contestant to perform. After their performance the judges should each give their "first impression critique" of the act. Have these be funny.
Typical phrases are things like,Then move on to the next performer until everyone has performed.
After everyone has sang, hand out one voting ballot (a ballot in the shape of a star) to everyone in attendance. The ballot should say "your name" with a line and "the next American Idol" with a line. This includes contestants, guests, judges, the technician, host and anyone who opted to be a back up dancer. The rules are, you just can't vote for yourself!
Have everyone turn in their ballots before leaving for the intermission. You could have a star shaped platter where they lay their ballots or an "official ballot taker" on hand to collect them all.
Allow for an intermission time. Everyone is probably ready to stretch their legs, refill their drinks and generally laugh about the contest and the funny moments in it.
The intermission also gives you time to tally the votes and gives the judges time to vote for all the secondary certificate prizes.
The way it works is whoever got the most votes on the ballot cards is given the honor of winning the competition. They are the "American Idol". To keep feelings from being hurt, the secondary certificates ensure everyone wins. (Especially important if this is a kids or teen party. If it's a party for adults, hey they've got thicker skin.)
The judges will choose which contestants win which specialty certificate, making sure everyone gets one. Have them write the name of the winner on each certificate.
The winner of the whole competition could get either a fancier certificate or a prize of some sort, like a music cd, gift certificate to a music store, or even a funny homemade hat that says something like "Move Over. I'm the Next American Idol".
After everyone has had a chance to take a break, cue the American Idol theme music again and have your host call everyone back for the Awards Ceremony. You can dress up the ceremony with a red carpet, stars on the wall, dimmed lights, and dramatic theme music in the background.
The host calls up the winners, and the winners "walk up the red carpet" to give their acceptance speech and get their certificate. Save the Idol Winner for last.
Follow the whole thing with the SuperStar banquet. Serve up the food for the party and the birthday cake. Fun ideas in keeping with the theme are finger foods cut out into the shape of stars (use a star cookie cutter). For adults things like pesto on whole grain toasted bread. For kids it could be jam on regular bread.
It's not hard to put on American Idol birthday party games like this contest. You can switch things out, simplify it, and change it so it suits your party. If it's for a younger kids birthday party, keep it shorter and simpler. If it's for teens or adults, they'll want all the extra excitement that comes from the Awards Ceremony and Banquet! Either way, enjoy your American Idol birthday party. Yo-dawg, it's going to be in perfect pitch!