When my husband turned 50 I threw him a surprise party.  The theme was "Celebrate Youth" rather than the regular over the hill parties thrown for 50 year olds.  I rented a local community party room.  Hired a DJ/Karaoke. I decorated in bright colors and balloons.  I displayed many items that he has saved from his younger days on a table labeled "Souvenirs from Jim's Youth": lava lamp, high school diploma, platform shoes, etc. I baked a cake that was 8 feet long and 4 inches wide and decorated as a time line.  I mounted pictures of my husband, at various ages, on skewers and poked them into the cake at the appropriate year/age on the time line. I used a scanner and computer to print some of the same pictures onto sticker type paper, cut them out and stuck the pictures onto all the plastic cups.  The guests had a great time comparing pictures on their cups. I had posters hung around the room - one with the current events from the year he was born, one with the top 10 reasons he made it to 50 years old. I also had a  life size cardboard cutout of my husband that stood in the corner of the room.  Guests were asked to dress up in silly costumes (which I provided) and have their picture taken with the cardboard cutout. I made the cardboard cutout - I asked a local grocery store for a cutout of Mike Ditka that was in a sales display.  I shaved off a few pounds, painted over the food item he was holding, and glued a picture of my husband's face over Mike Ditka's face. It looked great, for only the cost of the paint. All the guests sang and danced all evening.  It was great fun!