Throwing a surprise party for someone is not very difficult and can be done carefully with a little bit of planning. Although the traditional way is where all friends and family are hiding in the house to surprise the person when he/she enters, there are several other options that will be really liked by the person.
The most important factor that has to be kept in mind is careful planning. Before you finalize a date, make sure that the person in the honor of whom you are hosting the party has no other plans on that particular day. Request your friends to help you with the arrangements.
Send invitations and clearly state that it's a surprise and in no way should be revealed to the guest of honor. It is better to avoid having any theme where invitees are present in fancy clothes because the guest of honor may feel a little awkward. Hence, make sure that all guests come in casual attire.
Arrange for the food and ask your friend to bring it along with him/her. In this way, he/she does not know about the actual plan and will pleasantly shocked on seeing everyone arriving at the scenes minutes later.
Make necessary arrangements beforehand and inform the manager of the restaurant about the number of guests you are going to have. Take your friend under the pretext of a quiet dinner. The other guests will be assembled in the party area prior to your arrival. Now, make sure that you guide your friend to them and the wonderful surprise that awaits.
For instance, if he has ever talked about a particular friend he knew at college, but had lost touch with him or her, try to contact that person and invite him/her. Hold this information from your father and when the party is in progress, introduce this new person to the celebration. This will surely be the best retirement gift for your dearest father.
However, make sure that the kid in question is at least seven or eight years of age, as kids below this age may not understand the concept. Place clues at several places and do not forget to place a gift with each clue. You can arrange for the game at home or in your neighborhood where you can take the kid according to his/her instructions.
These are just some ideas and you can actually come with some more interesting ones if you put your mind to it. Have a blast!