I saw the "washer and dryer" trick performed exactly once. The "buildup" worked like this: Some guys walked up to my friend Vern while he was sitting in the lunchroom of the building where we all worked. They said, "Hey, Vern! We're having a drawing for a washer and dryer. Quick! Write your name on a slip of paper and drop it in the hat!"

I'm sure Vern knew right away something was fishy, but the only way he would hear the punchline was if he played along. So after a bit of delay and cajoling, he did as requested. His was the only slip in the hat. After a bit more hocus-pocus, they "drew" his name out of the hat and announced, "Hey, Vern! You won a washer and dryer!" They then presented him with his winnings.

You needn't worry that anyone was "hurt or seriously disappointed."

In my experience, most practical jokes work this way. The "victim" knows his leg is being pulled somehow; he just can't figure out what the punchline will be.

Also, most "practical jokes" are funnier to talk about than to actually perform.

In fact, I suspect some "practical jokes" are really just urban legends—they perhaps never really happened, or weren't pulled off quite as successfully as described, but the story of them gets told over and over.