when my step dad turned 50 he didnt want a huge 50th birthday party so instead we gave him a 50s birthday party.i dont know if it will go with the surprise party thing but you can wear poodle skirts and the guys can wear jeans and a white shirt (w/ a leather jacket if you want) and their hair slicked back. Play 50s music and dance and have a picnic out side with great burgers straight from the grill! Have fun
~xoxo sarah~