My favorite was my junior year of college when my friend and I were heading to Baylor University (baptist) for a party with some friends. We were drinking at like 2 am one night and the idea just hit us...went to wal-mart and bought all of our materials and stayed up all night making our costumes.
i got an old hat and set it up backwards and used great-stuff foam to shape it into a Penis head. I also ran some air-line tubing from the tip down through the hat (you'll see why later). After the foam dried it was cut to shape, covered in duct tape, and painted it a skin color. it is now a penis-head that you can wear as a hat, and has a small tube to run fluid trough and out the tip
For the body, I died some white pants and shirt a skin color, and took a purple sharpie and drew veins all over them. For the balls I did the same with a pillowcase, hung it from a belt, and put 2 of those big bouncie balls from wally world in it. To top it all off, I wore a black sport-jacket and called myself a "Corporate
Dick".
Now, I'm about 5'9, and my friend is about 6' tall, so he decided he needed to go as a ruler and we'd just walk around together all night. So like 10 sheets of yellow posterboard and a lot of black sharpie pen, some cuts, and some staples, and he's a 6'6" tall ruler, labeled up to 8 inches or something like that.
In the course of the night, I had dozens of women fondle my balls, including a few that were married. I gave out a few pearl necklace's, a few face shots, and a few back shots, I even had a swallower. Keep in mind though, we are on a Baptist universities campus doing this