If you are planning a surprise party idea for a man in your life, think about what kind of man he is. Some men are into sports or the outdoors; some just concentrate on their romantic desires. Other men might not enjoy any of those activities. Pick a surprise party that you think will appeal to him personally.
Secretly buy tickets for your man and you while telling him you have reservations at a fancy restaurant. Stress that he dress extremely nice so that he doesn't suspect the casual party. Pack a stash of team-appropriate clothes and anything else he might need at the game. Meanwhile, make sure all of the man's friends are already tailgating and ready for him to arrive. The party can involve plenty of burgers, hot dogs, chilli and a sports-themed cake. Create an excuse to get into the car park such as picking up a borrowed book. It may be tough to find an excuse that will trick him completely but do your best. When he sees all of his friends grilling up a storm and a big birthday cake, he'll know right away his surprise party has begun.
Drive the man to the nearest paintball field for an exciting party. Make an excuse such as a trip to an outlet mall or visiting a relative. Pack some paint-friendly clothes. The man's friends and family can drive ahead and be ready to greet him with a big "surprise!" when he arrives.
The camping surprise party is a less expensive than paintball, but still requires a drive to what seems like the middle of nowhere. Secretly invite your man's best friends to be both guests at the party and overnight campers. Drive the man toward the camping site after guests have set up the site, cake and food. Have a friend ask to "borrow" some camping clothes or supplies a few days beforehand so a bag of camping stuff will be waiting for him. If the man in your life is extremely outdoorsy, this may be one of your best bets.
While not all women may be comfortable with this, some men would want nothing more than an adult entertainer at their parties. Hire a licensed adult entertainer; check your phone directory for a list. Tell people to hide and surprise like normal---but as soon as the entertainer comes out, the man will know someone went the extra mile for him. Make sure this is what the man wants; an uncomfortable birthday guy will make the guests uncomfortable, as well.
Since all men don't fit in one particular category, think deeply about what your man likes and base your surprise party around it. A man who likes cars will enjoy a different type of party than a man who loves the theatre. There are many other surprise party ideas such as a rock-climbing party or a nostalgia party (set in a certain decade or year) that may be up your man's alley.