One of my favorite things to say when a child comes up to ask for something is,
"No. But I'm glad you came and asked me because now it's time to..."
And then I fill in the blank with something kids really, really LOVE doing.
For example, I'll say:
"...it's time to come inside."
"...it's time to clean up."
"...it's time to take a shower."
"...it's time to brush your teeth."
"...it's time to go to bed."
It's like super powerful magic.
They run off leaving me alone as quick as me on dark chocolate.
And that's sayin' something.