Tell someone to hold an empty beer bottle level with their face. Then place a cigarette butt balanced half way in and half way out of the bottle.

Objective:

Blow the butt into the bottle.

Solution:

Every time they blow at the ciggarette, the air will bounce off the back of the bottle and blow the butt back at them instead of into the bottle

Put a staw up to the butt and focus all of the air to the butt. In it goes. (Boy, If read alone, this last line could really be taken out of context)