Split the group in half. Those who are 'on / it' have to tag others. When tagged, the child becomes a toilet! They have to kneel on one knee, arm up for the flush and other knee (foot on floor) flat for the toilet seat.
To be released, someone from your team has to go to the loo on you and flush your chain. No one can tag you whilst you're on the loo. Swap over after 10 minutes.
A funny, physical and thoroughly enjoyable game!