Make "Sponge Bombs" and gather some neighbourhood kids (and adults) together along with a few buckets of water for a fun water fight. unlike water balloons you won't have pick up a ton of shriveled latex balloon pieces afterwards.
Make your own Sponge Water Bombs (alternative to water balloons). Cut sponges in strips crosswise, then stack 4 wide, 2 deep and tie very securely in middle with fishing line. Soak, play, have sponge water fight!