Earbuds by Adam Wilber
You can leave the card fused onto the spectator's earbuds, or have them tear it off, letting them feel the cord ripping through the solid card themselves.
Adam Wilber goes into great detail about not only how to perform this effect, but how to perform it well. He discusses handling ideas, included those suggested by Brad Christian, to ensure you get the utmost out of this effect.
Adam teaches two methods of accomplishing this feat, including one where the spectator can walk away with the SIGNED card still attached to their cord. This effect has been real world tested, and it shows, with Adam giving away more than a deck of souvenirs a week, and performing this effect at corporate gigs as one of his favorites.
With 30 minutes of detailed instruction, multiple angles and in-depth teaching, Earbuds can be performed the same day it's downloaded.
Run-time: 30 minutes