The Celebrity Name Trick
Then you need to tear off the sheet of paper, fold it, and put it in the hat. Nobody can see what you’re writing. Ask for more names, but only write the same name each time (i.e., Brad Pitt). You can stop when you had 10 or more pieces of paper in the hat when someone called out the name of the person you have written down in the envelope. With more names in the hat, the illusion will be better.
Source: 960theref.com
Then ask a volunteer to choose a paper from the hat and read out the name (which they will definitely pick “Brad Pitt”). Emphasize the fact that there’s no way you could know which name they would pick. Then ask them to open the envelope and see the prediction you made. Brad Pitt! You can take it up a notch and put a photo of the person in the envelope rather than writing their name.