It's this simple:
you vanish a pen WHILE THE SPECTATOR HOLDS IT.
Doing magic with pens has built-in appeal, since everyone carries them, you can borrow them anywhere, and they are uniformly recognized. How AMAZING it is, then, when you can take a pen and wrap it in a napkin. The spectator holds the napkin with the pen VISIBLY dangling beneath. You clap your hands together and...instantly...the pen disappears. This is a practical, astounding illusion with the simplest of objects.