Make a backyard bowling alley. Add food coloring to clear plastic bottles of water. Use party streamers as lane margins. Add glow sticks for night bowling. (These would make great outdoor table nightlights also with the glowsticks, gonna try it!
This Blows! Using a straw, see who can blow a series of plastic cups off the end of the table first. Another spin on this game is to use the air from a balloon instead of a straw to move the cup – this makes it much more challenging!