Pulling of the ultimate practical joke can take timing, research and a good bit of setup. Allow me to illustrate my point. Many years ago, I was working in the retail sales market. The actual job didn't bring me much pleasure, but it paid the bills and the people I worked with were great. The management left a good bit to be desired, but my co-workers and I always had a good time working there and interacting with each other.

Know your victim well

Of course, you should get to know the friend (or future victim) fairly well to understand their "triggers" or which "buttons" they have to set them off and scare the heck out of them. And, of course, be certain they have a really good sense of humor. You may want to test this by performing a couple of small practical jokes such as glueing the phone receiver down or a few coins to the floor next to their desk. But, this is minor stuff and nothing compared to what you may come up with in the future.
In general conversation with a certain friend, I was able to determine that she had a huge issue with crawling insects and cockroaches. I also watched her routines as she came to work. We are, of course, creatures of habit. She would clock in, then go straight to our merchandise storeroom and put her personal items on the desk and check a few things, before doing anything else.

Yes, this was much too easy and funny to let pass by. So, the planning begins!

Know your surroundings

Knowing the friend's habits, routines and, in this case, work schedule is important. Also, knowing what you have available to you in the work area can be quite helpful as well. As I mentioned, it was a retail job and we had a ton of hardware supplies and sporting goods equipment in the immediate vicinity. Additionally, we had a fairly large storeroom with six rows of wooden shelving units down each side as you entered the door.

Also, the storeroom was back in the corner of our area and somewhat secluded for esthetics, of course. The perfect setting for the practical joke I had in mind. So, I was able to have quick access to clear monofilament fishing line, several small pulleys and a plethora of other items. What more could one ask for!?

Planning the Practical Joke

I check her schedule and selected the day for the practical joke. I worked the shift just before hers and came in a little early. During my break, I setup several of the tiny pulleys and ran the monofilament fishing line through them and attached one end to the top of the door. The other end was attached to the 12" rubber cockroach that I also sprayed the bottom with non-stick cooking spray to ease it's travel across the floor. Additionally, this huge rubber cockroach had several large appendages that simple created the ultimate scary illusion. So, I attaced the cockroach inline with the monofilament fishing line and then again back to the door.

I strung it in such a fashion that when you opened the door, the huge rubber cockroach would quickly come scurrying across the floor towards you. Then, when you closed the door, it would slowly retreat back to it's original position. This took nearly two hours of adjusting pulleys and lenghth of the fishing line. But, as you can imagine, it was well worth it.

Document the event

Across from the storeroom door, I hid a small digital movie camera. No, I wasn't going to upload the video to the Internet or anything, but I knew I had to catch this event on video for future refernce! Come on, there are some events in life that you simply must preserve!

Like clockwork, she came on shift. She came by and we talked for a few minutes and I told her that I had to get going, because I had a date that night. I inconspicuously excused myself so that she could get into her normal routine. And, just as planned, she first went to the rear of our area and into the storeroom. I was about 50 feet away, concealed behind a few merchandise racks and suddenly heard the blood-curdling scream. A few other co-workers hurried over and we all quickly met at the storeroom entrance where she was red with fright and shaking just a bit, but we all were laughing so hard I nearly wet my pants. She began beating on me a bit, but knew immediately what I had done and totally appreciated the timing, setup and execution of this perfect practical joke.

A few days later, she pulled me aside, told me to never do that again! But, she also told me, it was the best joke ever and she will never, ever forget it and we all now have a memory that will live on and a really funny story to tell when hanging out with friends.