If you're planning a 50th birthday surprise party, be ready for a little bit of work, and a lot of fun!

One of the most popular 50th birthday party ideas is to throw one with a '70s theme. Although a 50 year old was born in 1961, they were in high school in the 1970s and tend to identify with this era the most. It will be a trip down memory lane for the the birthday person and all the guests, too. When you're inviting the guests, tell them all to dress in 1970s style. In case they can't remember what kind of crazy clothes people wore back then, give suggestions like: bell bottoms, hot pants, anything polyester, flared hip huggers, fake fur, boots, and platform shoes. Men wore their shirts open at the top by leaving the buttons open. Head bands, tie dye tee-shirts, Levi's, lots of love beads, tinted round glasses, and dangly earrings were also popular. A thrift store is a great place to shop for these things.

Make a collage of photos of the birthday person that you collect from friends and family. Draw out a time line from childhood to the present leaving room at the bottom so guests can write down their fun memories of the honoree. In the invitation, ask people to speak at the 50th birthday party about the person you're all celebrating. Tell them to bring their best story ideas to the party. This way everyone can learn more about the 50 year old, and it can make great entertainment. It's similar to a "roast' in that it's all in good fun.

Play lively music from the '70s at your 50th birthday party. Ideas like: "Born to Run," "Brick House," "Y.M.C.A.," "Disco Inferno," "Last Dance," and "Play that Funky Music" are great choices. Hand out disposable cameras to the guests so you'll have great memories of the party.

Ideas for decorating the 50th birthday party go from balloons and streamers to an "over the hill" theme. Be sure to take into consideration how the 50 year old feels about this milestone birthday; some people are overly sensitive, so keep that in mind.

Ideas for munchies include chips and dip, raw vegetables, cheese and crackers, canapes, tapas, non-alcoholic drinks, retro candy, and birthday cake. It's best to keep the 50th birthday party simple; that way you can concentrate on having fun. If you make this a memorable occasion for everyone, you've done a great job!