Required Items:  2 shot glasses, water, and straw.

Set-Up:  Place the shot glasses lip to lip and submerge them in a sink of water.  Fill both and place on the bar.

Trick:  To get the water out of the top shot glass, while keeping both glasses lip to lip.

Rule:  Bar-Fly may not touch either glass physically with anything.

Solution: Blow on the seal of the glasses to displace the water with air blown from the straw. Get out the bar rag.