Did someone say water balloon fight? Fill those bad boys (or girls) up faster with this simple attachement to the end of a garden hose. This design has a 3/4NPT threaded attachement and a lip for a standard hose gasket.

With a simple adapter, you can also attach this to the end of a commercial faucet. The faucet would have to have threads on the inside of the aerator. 

https://tinyurl.com/FaucetAdapterFunnel