Originally Posted by Beejeebers

He has an assistant scuba diving under the boat who plants the card on the window. The window is prepared ahead of time so you can't see his arm come up when the scuba guy, (I'll call him scuba steve), sticks it to the window. Notice how you never see the side where she writes on it?

Then he has the real card in his napkin the whole time and pretends to reach through the window, but scuba steve is removing the card from the window, (probably using a fishing line attached to it or something).

The only tricky part is the timing for sticking it on the window.

I give it 5 out of 10.