Things to remember when babysitting...

If you and your young charge have spent the last half an hour or so merrily throwing buckets of water around the garden, splashing each other, making 'raindrops' and generally having a glorious if soggy time, do not then sit on the lawn.  It will be damp!  And you will have a soggy patch on your trousers, causing your small person to laugh so hard they get a damp patch on their trousers, necessitating in a change of clothing for them.