Supplies:

Start with two empty beer bottles and a match.

Objective:

Tell a friend to light the match using nothing but the bottles.

Solution:

Firmly hold one bottle next to your chest rub the other bottle hard against the first using the bottom of the second until it scratches the first bottle.  Keep this up for about 15 seconds or until you have a nice size scratch mark. Using the match strike against the scratch until match lights.