For this game, you just need a penny and a 2-liter bottle.
Explain to your guests that each of them will soon know what it feels like to be pregnant and have to use the restroom really really bad. Each guest will place a penny between their knees and stand at the edge of the room. They will then have to walk to the center of the room and drop the penny into the 2-liter bottle. Whoever gets the penny into the bottle wins!
For this game, you might have several unopened 2-liters of pop as prizes for whoever makes it.