For my husband's 40th birthday, I did a retro 80's with the Delorean car from Back To The Future movies as a theme.  I had a lady to make me a cake with a Delorean drawn on it in icing. I used electric blue and silver as my colors.  Lots of ribbons and balloons which I weighted down with silver weights from the $1 store. I placed Cabbage Patch dolls and Rubix cubes around the room and handed out Pop Rocks.  Everyone was asked to dress in 80's clothing & I asked them to bring an old photo of my husband from the 80's which totally embarrassed him. I also displayed his baby pics, high school pics & our wedding pics in a black leather photo holder.  Some I displayed by placing on a large white cardboard sign (that had birthday balloons on it) using sticky photo corner-holders that you can buy at Walmart in the craft section and displayed the sign on his gift table. I also took blue and white cardboard (again from the $1 store) and wrote out 80's Slang (cool, awesome, like totally, chill, as if?, gag me with a spoon, etc..) and I also did "You're a child of the 80's if..." (you wore slouch socks with leggings, you can name all the cast of The Breakfast Club, you ever wished you owned a Delorean, You thought Ghostbusters was the coolest movie, You remember Punky Brewster, Alf, and Webster, You wore a banana clip, slap on wrist bands and rolled up the bottom of your splatter painted jeans!, etc..) I got a lot of this on the internet.  I added a clock with the hands going back in time starting with 2003 back to 1985.  I almost was able to borrow an actual Delorean car to have at the party but it fell thru. Great idea though. He got lots of gag gifts and a replica mini-Delorean which was cool.  I also bought a Sundrop sign and wrote Happy 40th Birthday to place out in the front yard and I decorated his truck with lots of Turning 40's banners, etc. that I got from The Party House. Pulled out ATARI set, breakdance music & played Back To The Future movie rental. He was TOTALLY surprised and everyone had an AWESOME time!